Preheat your oven to 350°F (175°C). This ensures the muffins bake evenly and rise properly.

Line a muffin tin with paper liners or grease it with non-stick spray to prevent sticking.

In a large mixing bowl, whisk together the dry ingredients: flour, baking soda, salt, and cinnamon. Whisking helps to evenly distribute the leavening agent.

In another bowl, combine the mashed bananas, granulated sugar, brown sugar, melted butter, beaten egg, and vanilla extract. Mix until well combined.

Pour the wet ingredients into the dry ingredients. Gently fold them together using a rubber spatula until just combined. Be careful not to overmix, as this can lead to dense muffins.

Fold in the chocolate chips until evenly distributed throughout the batter.

Spoon the batter into the prepared muffin tin, filling each cup about ⅔ full. This allows room for the muffins to rise.

Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean. This indicates that the muffins are fully baked.

Once baked, remove the muffins from the oven and let them cool in the tin for about 5 minutes.

Transfer the muffins to a cooling rack to cool completely. This prevents them from becoming soggy.