Bright citrus zing softened with sweetness and leveled out with a buttery graham cracker crust – this key lime slab pie is an absolute dream to sink your teeth into.
Why this recipe works
This easy key lime slab pie is tangy, sweet, and all around the best dessert to usher in those warm sunny days with. It starts with a graham cracker crust that climbs the rim of the baking pan and holds all that key lime custard in its place. Top with pillows of fresh whipped cream and lime zest, and that’s it. Isn’t she a stunner?
Key lime slab pie is easier to prep in advance so it has plenty of time to mingle in the pan before shoveling into your mouth. I know it might be hard to wait for something so tantalizing to chill, but it’s worth every last pace back and forth to the fridge to peek in on it. Your guests will thank you, but I honestly couldn’t judge you if you kept more than half of this one to yourself.
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
CRUST – You can use prepackaged graham cracker crumbs for this crust. If you grind up the crackers yourself, you will need about 3.5 sleeves, which is roughly 30-32 crackers. Keep in mind that not all brands are created equal and might not contain the same number of crackers! It’s best to measure and even weigh the crumbs (see weights in the ingredient list).
LIMES – To make a genuine key lime pie, you will need the juice from key limes. Key limes are small and you will need about 30 of them, which is approximately 2 pounds. Because of their size, they are a pain to juice and not truly necessary. Instead, you can use regular limes, and if you’re really in a pinch, bottled lime juice. We do recommend juicing limes yourself as it simply tastes better than the bottled stuff!
EGGS – Separating eggs is easiest when the eggs are cold. I have found that it’s best to use 3 bowls: 1 for separating the egg over, 1 for the yolks, and 1 for the whites. We suggest this in case a yolk breaks, it doesn’t contaminate the already separated whites, especially if you plan to use the whites for something like meringue or our angel food cake!
TOPPING – Instead of whipped cream, you can make a meringue from the egg whites. To do so, place the leftover room temperature egg whites into a large bowl. Use a mixer to whip the whites until glossy. Next, mix in 1/2 teaspoon of cream of tartar. Slowly add in 1/2 cup of sugar, beating until stiff peaks form. This meringue can be spread on top of your prepared pie, using a spoon or rubber spatula to gently lift meringue into peaks. Brown your meringue in a hot oven (watch it closely) and/or use a kitchen torch.
How to Make Key Lime Slab Pie
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.
- Preheat oven to 350 F. Spray 10×15 baking pan with non-stick cooking spray.
- Combine crust ingredients in a bowl and mix well.
- Press crust mixture evenly into the bottom and up the sides of the baking pan.
- Bake the crust for 10 minutes in a preheated oven. Cool on a wire rack.
- In a large bowl, whisk together sweetened condensed milk, lime juice, and egg yolks until the mixture thickens.
- Pour filling into the cooled crust and spread evenly with a rubber spatula.
- Bake until set, about 10 minutes. The center will jiggle slightly when the pan is nudged.
- Cool completely on a wire rack.
- Refrigerate until cold, at least 4 hours or up to 24 hours.
- To make the topping, with a mixer at low speed, combine heavy whipping cream and powdered sugar until sugar is no longer visible.
- Increase speed to medium until mixture begins to thicken, then increase speed to high. Whip until firm soft peaks form.
- Spread whipped cream on top of the chilled pie.
- Garnish with lime zest and lime slices if desired.
Frequently Asked Questions & Expert Tips
Yes, this slab pie freezes well! You can freeze it with or without the whipped topping, but from my testing, it holds up longer without the topping. Flash freeze the slab pie until mostly solid then wrap it tightly with a couple of layers of aluminum foil if you plan on storing it in the pan. Otherwise, you can slice the pie after flash freezing and individually wrap and store the slices in an air-tight container.
Yes, absolutely! This pie is actually best prepared a day in advance or the morning you plan on serving it to allow yourself enough time for cooling and refrigeration. I would recommend waiting to add the whipped topping until just before serving if you are prepping the pie in advance.
Store any leftovers in an air-tight container kept in the refrigerator for 2-3 days.
Serving Suggestions
Garnish your key lime slab pie with whipped cream or homemade meringue topping with a sprinkle of lime zest and/or sliced limes. It’s best enjoyed chilled and in giant spoonfuls, if you know what I mean.
Slab pies are excellent for large parties or potlucks. Because they are thinner and much larger than a traditional circular pie, you’ll yield double the number of servings.
More Slab Pie Recipes
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Key Lime Slab Pie
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
Crust
- 3 ½ cups graham cracker crumbs 16.8 ounces, 476g
- ½ cup granulated sugar 4 ounces, 117g
- 1 cup unsalted butter melted, 16 tablespoons or 226g
Filling
- 28 ounces sweetened condensed milk two 14 ounce cans, 2.5 cups, 763g
- 1 cup lime juice 8 ounces, 237g
- 8 large egg yolks
Topping
- 2 cups heavy whipping cream 16 ounces, 450g
- 2 Tablespoons powdered sugar
- lime zest and lime slices as garnish
Things You’ll Need
Before You Begin
- Separating eggs is easiest when the eggs are cold. I have found that it’s best to use 3 bowls: 1 for separating the egg over, 1 for the yolks, and 1 for the whites. We suggest this in case a yolk breaks, it doesn’t contaminate the already separated whites, especially if you plan to use the whites for something like meringue or our angel food cake.
- To make a genuine key lime pie, you will need the juice from key limes. Key limes are small and you will need about 30 of them, which is approximately 2 pounds. Because of their size they are a pain to juice and not truly necessary. Instead, you can use regular limes, and if you’re really in a pinch, bottled lime juice. We do recommend juicing limes yourself as it simply tastes better than the bottled stuff!
- You can use prepackaged graham cracker crumbs for this crust. If you grind up the crackers yourself, you will need about 3.5 sleeves, which is roughly 30-32 crackers. Keep in mind that not all brands are created equal and might not contain the same number of crackers! It’s best to measure and even weigh the crumbs.
Instructions
Make the Crust
- Preheat oven to 350 F. Spray baking pan with non-stick cooking spray.
- Combine crust ingredients in a bowl and mix well.3 1/2 cups graham cracker crumbs, 1/2 cup granulated sugar, 1 cup unsalted butter
- Press crust mixture evenly into the bottom and up the sides of the 10×15 baking pan.
- Bake the crust for 10 minutes in a preheated oven. Cool on a wire rack.
Make the Filling
- In a large bowl, whisk together sweetened condensed milk, lime juice, and egg yolks until the mixture thickens.28 ounces sweetened condensed milk, 1 cup lime juice, 8 large egg yolks
- Pour filling into the cooled crust and spread evenly with a rubber spatula.
- Bake until set, about 10 minutes. The center will jiggle slightly when the pan is nudged.
- Cool completely on a wire rack.
- Refrigerate until cold, at least 4 hours or up to 24 hours.
Make the Topping
- With mixer at low speed, combine heavy whipping cream and powdered sugar until sugar is no longer visible.2 cups heavy whipping cream, 2 Tablespoons powdered sugar
- Increase speed to medium until mixture begins to thicken, then increase speed to high. Whip until firm soft peaks form.
- Spread whipped cream on top of the chilled pie.
- Garnish with lime zest and lime slices if desired.
Expert Tips & FAQs
- Store any leftovers in an air-tight container kept in the refrigerator for 2-3 days.
- Make Ahead – This pie is best prepared a day in advance or the morning you plan on serving it to allow yourself enough time for cooling and refrigeration. I would recommend waiting to add the whipped topping until just before serving if you are prepping the pie in advance.
- Freezing – You can freeze it with or without the whipped topping, but from my testing, it holds up longer without the topping. Flash freeze the slab pie until mostly solid then wrap it tightly with a couple of layers of aluminum foil if you plan on storing it in the pan. Otherwise, you can slice the pie after flash freezing and individually wrap and store the slices in an air-tight container.
Nutrition
Amanda Davis
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