These double chocolate zucchini muffins are deeply fudgy, loaded with chocolate chips, and bakery-tall with grated zucchini hidden right inside. You won’t even be able to tell their base starts with a veggie!
Why this recipe works
I tested these muffins 4 times before I landed on the perfect batch. The double chocolate comes from two places, unsweetened cocoa whisked into the batter and dark chocolate chips folded all the way through, so every bite is genuinely rich and chocolatey instead of just sweet. The sour cream is my secret for a tender, moist crumb, the same trick that makes our double chocolate zucchini bread so good. The grated zucchini melts right in, adding moisture without any vegetable flavor coming through.
The tall, domed tops come from two simple techniques. I let the batter rest for 20 minutes before baking, which thickens it for a better rise, the same method I use for my cinnamon streusel muffins. Plus, I start the muffins in a hot 425 degree oven before dropping the heat, which forces a fast, bakery-style crown. Splitting the batter across two pans gives each muffin room to rise tall. Crammed into a single 12-cup pan, some of the tops spread and merge instead of doming. The other option is to make 14 muffins instead of 12. This is an easy, from-scratch recipe that bakes up looking like it came from a bakery case.
Ingredients you will need
Get all measurements, ingredients, and instructions in the printable version at the end of this post.
Ingredient Info and Substitution Suggestions
DARK CHOCOLATE CHIPS – These are half of what makes these muffins double chocolate, so I fold a generous half cup right into the batter. I prefer dark chocolate chips because they keep things from tasting too sweet against all that cocoa, but semi-sweet works too if that is what you have. I also scatter a handful of smaller semi-sweet chips over the tops before baking, since the smaller size sits and shows better up there than the larger dark chips.
UNSWEETENED COCOA POWDER – The cocoa is the other half of the double chocolate, whisked into the dry ingredients for deep flavor and color. I use natural unsweetened cocoa, but Dutch-process will give you an even darker, smoother result if you like.
SOUR CREAM – This is my secret for the softest, moistest crumb, and it is the same ingredient that makes our chocolate zucchini bread so tender, so please do not skip it. If you are out, full-fat plain Greek yogurt is the closest swap and works beautifully.
ZUCCHINI – Grated zucchini keeps these muffins incredibly moist without adding any flavor you can taste. I shred it on the small holes of a box grater, then squeeze and blot it firmly between paper towels until it weighs about 9.5 ounces. That blotting step matters, since too much moisture is what makes muffins gummy. There is no need to peel it.
INSTANT COFFEE GRANULES – A teaspoon of instant coffee is my favorite trick for making chocolate taste more chocolatey. You will not taste coffee at all, it just deepens the cocoa. Espresso powder works too, and since it is more concentrated I use about half a teaspoon in its place. If you would rather leave the coffee out entirely, a teaspoon of ground cinnamon is lovely as well!
BROWN SUGAR – I use a mix of granulated and brown sugar. That little bit of brown sugar adds moisture and a soft molasses note that rounds out the chocolate.
OIL – A neutral oil like vegetable or canola keeps these muffins moist and tender, and it means the batter comes together with just a whisk, no softening butter or mixer required.
How to Make Double Chocolate Zucchini Muffins
The weights listed in the recipe are the measurements I tested, and since volume scoops can pack heavy, weighing is the most reliable way to reproduce these muffins.
Both paper liners and butter-and-cocoa release cleanly; the buttered-and-dusted muffins rise a touch higher. Cooking spray can leave a tacky film on the exterior, so skip it.
These step by step photos and instructions are here to help you visualize how to make this recipe. You can Jump to Recipe to get the printable version of this recipe, complete with measurements and instructions at the bottom.
- Shred the zucchini on the small holes of a box grater. You should get roughly 3 cups shredded from 14-15 ounces of zucchini. Lay down two layers of paper towels and spread the shredded zucchini onto it. Place two more layers of paper towels across the top and blot it firmly with the palms of your hands until it weighs 9.5 oz (about 1¾ cups packed). Set aside. Blotting to weight is what keeps the crumb from turning gummy.
- In a large bowl, whisk together the flour, cocoa, baking soda, baking powder, salt, and coffee granules.
- In a small bowl, toss the 1/2 cup dark chocolate chips with a spoonful of the dry mixture. Coating the chips keeps them from sinking as the muffins bake.
- In a medium bowl, whisk together the oil, granulated sugar, brown sugar, eggs, vanilla, and sour cream until smooth and well blended.
- Add the wet mixture to the dry and stir just until barely combined; a few flour streaks are fine. Fold in the blotted zucchini, then the floured chips. Do not over mix, or the muffins will turn tough.
- Let the batter rest 20 minutes. This hydrates the flour, relaxes the gluten, and thickens the batter for taller crowns, and it lets the flour absorb moisture from the zucchini for a better-set crumb.
- Preheat the oven to 425°F during the rest.
- Line two muffin pans with paper liners (6 in each pan, not all 12), or butter the wells and dust with cocoa (avoid cooking spray, which can leave a tacky film on the muffins). Divide the batter among 12 cups across the two pans, 6 per pan, so they have room to dome without touching. Sprinkle the tops with the semi-sweet chocolate chips.
- Bake at 425°F for 5 minutes to force a fast rise and set the crown. Do not open the oven.
- Without opening the oven door, reduce the temperature to 350°F and bake 17 to 20 minutes more, until a toothpick inserted in the center comes out clean or with a few moist crumbs (not wet batter).
- Cool the muffins in the pans 5 minutes, then transfer to a wire rack to cool completely. They finish setting as they cool.
Frequently Asked Questions & Expert Tips
Nope! The grated zucchini melts right into the batter as it bakes, adding moisture but no vegetable flavor. Between the cocoa and the chocolate chips, all anyone tastes is chocolate.
You do not need to peel it, the skin softens completely and disappears into the batter. You do need to squeeze and blot it, though. Shred it on the small holes of a box grater, then press it firmly between paper towels until it weighs about 9.5 ounces. Removing that extra water is what keeps the muffins from turning gummy in the middle.
Almost always too much moisture from the zucchini, or slightly underbaking. Blot the zucchini to weight as described, and bake until a toothpick comes out clean or with just a few moist crumbs. The muffins also keep setting as they cool, so give them a few minutes before you judge the crumb.
Toss the chips with a spoonful of the flour mixture before folding them in, which helps them stay suspended. The 20-minute batter rest helps here too, since it thickens the batter enough to hold the chips in place.
If you want a shortcut, I have a whole post on easy cake mix zucchini muffins that you can make chocolate with a boxed mix. These from-scratch muffins are richer and fudgier, but the cake mix route is hard to beat for speed.
Storage and Freezing Information
Store the cooled muffins in an airtight container at room temperature for up to 3 days. Make sure they are completely cool before you cover them, or trapped steam can make the tops sticky.
To freeze, set the cooled muffins on a plate or cookie sheet so none are touching and freeze them for a few hours until solid. Then wrap each one in plastic wrap and drop them into a freezer bag, where they will keep for up to 3 months. To thaw, peel the plastic off while the muffin is still frozen and let it come to room temperature. Removing the plastic right away keeps it from sticking to the muffin as it thaws. You can also warm a muffin in the microwave for about 30 seconds for that just-baked feel.
Serving Suggestions
These are perfect with a hot cup of coffee for breakfast, or warmed for a few seconds so the chocolate chips go melty for an after-dinner treat. They make a great addition to a brunch spread, and I love setting them out alongside other zucchini favorites when the garden is overflowing, like a batch of fudgy zucchini brownies or a loaf of double chocolate zucchini bread for the chocolate lovers. A cold glass of milk is always welcome!
My youngest daughter loved these so much, she had one for breakfast and for dessert! I think she was overjoyed that I tested these 4 times and was able to be an official taste tester. Even my chef husband loved them!
More Zucchini Recipes
- Double Chocolate Zucchini Bread
- Zucchini Brownies
- Vanilla Zucchini Muffins
- Lemon Blueberry Zucchini Bread
- Easy Cake Mix Zucchini Muffins
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Double Chocolate Zucchini Muffins
IMPORTANT – There are often Frequently Asked Questions within the blog post that you may find helpful. Simply scroll back up to read them!
Print It Pin It Rate ItIngredients
- 14 ounces zucchini about 3 small
- 7.4 ounces all purpose flour 1 1/2 cups
- 1.31 ounces unsweetened cocoa powder 6 tablespoons
- ¾ teaspoon baking soda
- 1 ½ teaspoons baking powder
- ½ teaspoon salt
- 1 teaspoon instant coffee granules
- ½ cup dark chocolate chips 3 ounces
- 6 Tablespoons canola oil
- 6.46 ounces granulated sugar 3/4 cup
- 1.9 ounces brown sugar packed. 1/4 cup
- 2 large eggs
- 1 ½ teaspoons vanilla extract
- 3.4 ounces sour cream 6 tablespoons
- ⅓ cup semi sweet chocolate chips optional
Things You’ll Need
Before You Begin
- I use natural unsweetened cocoa, but Dutch-process will give you an even darker, smoother result if you like.
- There’s no need to peel your zucchini first. You won’t even be able to tell once they are baked.
- You will not taste coffee at all, it just deepens the cocoa. Espresso powder works too, and since it is more concentrated I use about half a teaspoon in its place. If you would rather leave the coffee out entirely, a teaspoon of ground cinnamon is lovely as well!
Instructions
- Shred the zucchini on the small holes of a box grater. You should get roughly 3 cups shredded from 14-15 ounces of zucchini. Lay down two layers of paper towels and spread the shredded zucchini onto it. Place two more layers of paper towels across the top and blot it firmly with the palms of your hands until it weighs 9.5 oz (about 1¾ cups packed). Set aside. Blotting to weight is what keeps the crumb from turning gummy.14 ounces zucchini
- In a large bowl, whisk together the flour, cocoa, baking soda, baking powder, salt, and coffee granules.7.4 ounces all purpose flour, 1.31 ounces unsweetened cocoa powder, 3/4 teaspoon baking soda, 1 1/2 teaspoons baking powder, 1/2 teaspoon salt, 1 teaspoon instant coffee granules
- In a small bowl, toss the 1/2 cup dark chocolate chips with a spoonful of the dry mixture. Coating the chips keeps them from sinking as the muffins bake.1/2 cup dark chocolate chips
- In a medium bowl, whisk together the oil, granulated sugar, brown sugar, eggs, vanilla, and sour cream until smooth and well blended.6 Tablespoons canola oil, 6.46 ounces granulated sugar, 1.9 ounces brown sugar, 2 large eggs, 1 1/2 teaspoons vanilla extract, 3.4 ounces sour cream
- Add the wet mixture to the dry and stir just until barely combined; a few flour streaks are fine. Fold in the blotted zucchini, then the floured chips. Do not over mix, or the muffins will turn tough.
- Let the batter rest 20 minutes. This hydrates the flour, relaxes the gluten, and thickens the batter for taller crowns, and it lets the flour absorb moisture from the zucchini for a better-set crumb.
- Preheat the oven to 425°F during the rest.
- Line two muffin pans with paper liners (6 in each pan, not all 12), or butter the wells and dust with cocoa (avoid cooking spray, which can leave a tacky film on the muffins). Divide the batter among 12 cups across the two pans, 6 per pan, so they have room to dome without touching. Sprinkle the tops with the semi-sweet chocolate chips.1/3 cup semi sweet chocolate chips
- Bake at 425°F for 5 minutes to force a fast rise and set the crown. Do not open the oven.
- Without opening the oven door, reduce the temperature to 350°F and bake 17 to 20 minutes more, until a toothpick inserted in the center comes out clean or with a few moist crumbs (not wet batter).
- Cool the muffins in the pans for 5 minutes, then transfer to a wire rack to cool completely. They finish setting as they cool.
Expert Tips & FAQs
- Store the cooled muffins in an airtight container at room temperature for up to 3 days. Make sure they are completely cool before you cover them, or trapped steam can make the tops sticky.
- To freeze, set the cooled muffins on a plate or cookie sheet so none are touching and freeze them for a few hours until solid. Then wrap each one in plastic wrap and drop them into a freezer bag, where they will keep for up to 3 months. To thaw, peel the plastic off while the muffin is still frozen and let it come to room temperature. Removing the plastic right away keeps it from sticking to the muffin as it thaws. You can also warm a muffin in the microwave for about 30 seconds for that just-baked feel.
Nutrition
The recipes on this blog are tested with a conventional gas oven and gas stovetop. It’s important to note that some ovens, especially as they age, can cook and bake inconsistently. Using an inexpensive oven thermometer can assure you that your oven is truly heating to the proper temperature. If you use a toaster oven or countertop oven, please keep in mind that they may not distribute heat the same as a conventional full sized oven and you may need to adjust your cooking/baking times. In the case of recipes made with a pressure cooker, air fryer, slow cooker, or other appliance, a link to the appliances we use is listed within each respective recipe. For baking recipes where measurements are given by weight, please note that results may not be the same if cups are used instead, and we can’t guarantee success with that method.
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