Prep the pan and oven. Heat the oven to 375°F (190°C). Line a 12-cup muffin pan with paper liners or lightly grease it. This temperature gives you a nice dome without drying the muffin.

Mash the bananas. In a large bowl, mash the ripe bananas until mostly smooth. A few small lumps are okay and add texture.

Whisk the wet ingredients. To the bananas, add granulated sugar, brown sugar, melted butter, oil, eggs, milk, and vanilla. Whisk until well combined and glossy.

Combine the dry ingredients. In a separate bowl, whisk flour, baking soda, baking powder, salt, and cinnamon. This distributes the leavening evenly so your muffins rise well.

Bring wet and dry together. Add the dry ingredients to the wet mixture. Use a spatula to fold gently until you no longer see dry streaks. Do not overmix; a few lumps are fine.

Fold in the chocolate chips. Gently stir in 1 cup of chocolate chips. Save a few to sprinkle on top for a bakery-style look.

Fill the muffin cups. Divide the batter evenly among the 12 cups, filling each about 3/4 full. Top with extra chocolate chips and a pinch of coarse sugar if you like a crisp top.

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

Cool. Let the muffins sit in the pan for 5 minutes, then transfer to a wire rack to cool. They’ll set up as they cool and become easier to handle.

Enjoy. Serve warm for melty chips, or at room temperature for a more set crumb. Both are great.