Prep the pan and oven: Line a 12-cup muffin tin with paper liners or grease lightly. Preheat your oven to 375°F (190°C). The slightly higher heat encourages a nice muffin dome.

Mash the bananas: In a large bowl, mash the bananas with a fork until mostly smooth with a few small lumps. You should have about 1 1/2 cups of mashed banana.

Mix the wet ingredients: Whisk in the melted butter, granulated sugar, brown sugar, eggs, and vanilla until well combined and glossy.

Combine dry ingredients: In a separate bowl, whisk together the flour, baking soda, baking powder, salt, and cinnamon.

Bring it together: Add the dry ingredients to the wet ingredients. Stir gently with a spatula until just combined. A few streaks of flour are okay—don’t overmix.

Fold in the chocolate: Gently fold in the chocolate chips (and nuts, if using). The batter will be thick and scoopable.

Fill the muffin cups: Divide the batter evenly among the 12 cups, filling each about 3/4 full. Sprinkle a few extra chocolate chips on top for a bakery-style look.

Bake: Bake for 16–20 minutes, or until the tops are set and a toothpick inserted into the center comes out clean or with a few moist crumbs (melted chocolate is fine).

Cool: Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. They’ll smell amazing—try to let them set a bit before you dig in.