Preheat the oven to 350°F (175°C) and grease or line a muffin tin with paper liners.

In a mixing bowl, whisk together the flour, baking soda, salt, and cocoa powder.

In another bowl, combine the mashed bananas, granulated sugar, brown sugar, vegetable oil, eggs, and vanilla extract. Mix until well combined.

Gradually add the dry ingredients to the wet ingredients, stirring until just combined. Fold in the chocolate chips.

Scoop the batter into the prepared muffin tin, filling each cup about 2/3 full.

Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.

Allow the muffins to cool in the tin for 5 minutes before transferring to a wire rack to cool completely.