Preheat your oven to 375°F and line a muffin pan with paper liners or grease the cups lightly.
In a large mixing bowl, combine the whole wheat flour, rolled oats, brown sugar, baking powder, baking soda, salt, and ground cinnamon.
In another bowl applesauce, Greek yogurt, almond milk, egg, and vanilla extract until well combined.
Pour the wet ingredient mixture into the dry ingredients and stir until just combined. Be careful not to overmix; it's okay if the batter is a little lumpy. Then gently fold the mango in the muffin batter.
Divide the batter into every other muffin cup, filling all the way to top
CRUMB TOPPING
In a small bowl, combine the rolled oats, whole wheat flour, melted coconut oil, brown sugar, and ground cinnamon for the crumb topping. Mix until crumbly.
Sprinkle the crumb topping evenly over the muffin batter in each cup.
Bake the muffins in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean and the oatmeal topping is crunchy
Remove the muffins from the oven and let them cool in the muffin tin for a few minutes before transferring them to a wire rack to cool completely.