Mango-Banana Oatmeal Muffins

Preheat the oven to 375°F (190°C) and line a muffin tin with paper liners or grease the cups thoroughly.

Combine whole wheat flour, all-purpose flour, oatmeal, brown sugar, baking powder, salt, and cinnamon in a large mixing bowl, whisking together to distribute the leavening agents and spices evenly.

Melt the butter over low heat or in the microwave, then let it cool slightly before whisking together with the beaten egg, milk, and vanilla extract in a separate bowl.

Fold the wet ingredients into the dry ingredients using a spatula or wooden spoon, stirring until just combined—the batter should have a slightly lumpy texture to prevent overdevelopment of gluten.

Gently fold the mashed banana into the batter until evenly distributed, then carefully fold in the chopped mango pieces, being careful not to break them apart further.

Divide the batter evenly among the muffin cups, filling each about three-quarters full to allow room for rise.

Bake for 25 minutes until a toothpick or skewer inserted into the center of a muffin comes out clean or with just a few moist crumbs.

Remove the muffin tin from the oven and allow the muffins to cool in the tin for 5 minutes before turning them out onto a wire rack to cool completely.