With a stand mixer, beat butter and brown sugar on medium speed until creamy.
6.35 ounces packed brown sugar, 1/2 cup unsalted butter
Add eggs and vanilla and beat just until combined.
1 teaspoon pure vanilla extract, 2 large eggs
Beat in pumpkin and bananas, beating just until combined.
4.5 ounces pumpkin puree, 2 overripe bananas
With a rubber spatula, stir in half of the dry ingredients. Stir in the buttermilk. Stir in remaining dry ingredients. Do not over mix, it’s okay if there are small traces of flour still showing.
2 ounces buttermilk
If adding mix-ins such as chips, nuts, or fruit, fold them into the batter now.
Let batter rest 30 minutes. This allows the oven to get nice and hot as well.
Fill liners to the top with batter.
Bake at 425F for 5 minutes. Without opening the door, turn oven down to 350F for another 15-18 minutes, or until a toothpick poked into the center comes out clean. Ours were done at the 16 minute mark.
Remove from oven and allow to cool in pan for 5 minutes, then remove to wire rack to cool completely.
Feel free to garnish the muffin batter before baking with any of the optional toppings listed above.
If you do not own a kitchen scale, aerate the flour gently, then scoop it into a measuring cup using a spoon until overflowing. Sweep off the excess using the back end of a butter knife to level it out. Never tap the measuring cup on a surface to compact, and do not scoop directly from the bag with the cup. Too much flour equals dry, dense baked goods.
You can easily add baking chips (cinnamon chips are amazing here), nuts, raisins, or other dried fruits as mix-ins for these muffins. See the tips mentioned in the post for measurements.