Healthy Banana Protein Muffins

In a large mixing bowl, combine almond flour, coconut flour, protein powder, baking powder, baking soda, and salt then whisk together.
Make a well in the center of the flour, and add eggs, then whisk.
Melt butter, and whisk in with the eggs.
Add in mashed banana and vanilla and brown sugar, then mix. Note the batter will be thick.
In a small bowl, combine the brown sugar and chopped walnuts.
Line muffin tins with paper liners. Scoop the batter into the muffin cups. Top with crumb topping.
Bake in a preheated 325-degree oven for 35-40 minutes or until an inserted toothpick comes out clean.
Cool completely on a wire rack. Can be served at room temperature or slightly warmed.
Store in an airtight container or bag for up to one week. These banana muffins can be stored in the freezer for up to three months then thawed at room temperature.