In a large bowl, whisk together the flour, granulated sugar, baking powder, baking soda, and salt. Set aside.
2 ½ cups all purpose flour, 1 cup granulated sugar, 2 teaspoons baking powder, ½ teaspoon baking soda, ½ teaspoon salt
In a medium-sized bowl, whisk together the melted and cooled butter, eggs, vanilla extract, milk, and mashed bananas.
½ cup unsalted butter, 2 eggs, 1 tablespoon vanilla extract, 1 cup whole milk, ⅔ cup mashed banana
Pour the dry ingredients into the wet ingredients and fold together until combined but with a few streaks of flour remaining.
Add the mini chocolate chips and gently fold, being careful not to over-mix, until the streaks of flour are gone and the chocolate chips are fully incorporated into the batter.
1 cup mini chocolate chips
Cover the bowl with plastic wrap and let rest at room temperature for 30 minutes.
Once the batter has 5 minutes left to rest, preheat your oven to 425F and line a muffin tin with cups leaving every other one empty. This isn't required but it will help the muffins rise tall & have room to spread on top of the pan.
Do not whisk or fold the batter again after resting. This will negate all the work the leavening agents just did. Scoop & plop the batter into the prepared muffin tin, filling them all the way to the top. Sprinkle more chocolate on top if desired.
Bake at 425F for 8 minutes. Then, without opening the oven door, reduce the temperature to 350F and bake for another 8-10 minutes for regular sized muffins or 17-20 minutes for jumbo.
The muffins are finished when a toothpick inserted into the center of the muffin comes out clean. *If baking the muffins in two batches, make sure you increase the oven temperature back up to 425F for the second batch of muffins.
Let the muffins cool in the pan for 20 minutes. Then invert onto a cooling rack to continue cooling. Enjoy still slightly warm or let cool completely. Store in an airtight container at room temperature.