“This was very fun. We had learned about fractions in school, and now we are using math. And chocolate chips. Yummy!” —Morgan, recipe tester, age 9
Adjust oven rack to middle position and heat oven to 375 degrees. Spray 24-cup mini muffin tin well with vegetable oil spray (make sure to get inside each mini cup!).
In medium bowl, whisk together flour, baking soda, and salt.
Peel bananas and place in large bowl. Use large fork or potato masher to mash bananas until broken down but still chunky.
Add sugar, melted butter, yogurt, egg, and vanilla to bowl with bananas and whisk until combined.
Add flour mixture and chocolate chips and use rubber spatula to gently stir until just combined and no dry flour is visible. Batter should look thick and chunky—do not overmix.
Spray 1-tablespoon measuring spoon with vegetable oil spray. Use greased measuring spoon to scoop 1 heaping tablespoon batter into each muffin tin cup.
Place muffin tin in oven. Bake until muffins are golden brown and toothpick inserted in center of 1 muffin comes out clean, 13 to 15 minutes.
Use oven mitts to remove muffin tin from oven (ask an adult for help). Place muffin tin on cooling rack and let muffins cool in muffin tin for 15 minutes.
This recipe calls for very ripe bananas, which are sweeter and moister than underripe ones. To tell how ripe your banana is, look at the peel: If the peel looks greenish and feels a little hard, your banana is underripe. If it’s bright yellow and a little bit soft, it’s ripe (perfect for snacking!). And if it has black or brown spots and feels very soft, it’s very ripe (great for baking). If you have too many very ripe bananas on hand, don't worry: freeze them to cook with later! Peel the bananas, place them in a zipper-lock bag, and put them in the freezer. Just thaw them before you bake.