Preheat the oven to 350° F.
Add the oat flour, whole wheat flour, vanilla protein powder, baking powder, and baking soda to a large mixing bowl.
Mix all dry ingredients thoroughly to combine.
Make a well in the center of the bowl, then add the maple syrup, nut milk, applesauce, and peanut butter.
Mix all wet ingredients to combine, then slowly mix the wet ingredients into the dry to form a smooth muffin batter.
Gently fold in the rainbow sprinkles, reserving some to top the muffins with if desired.
Evenly distribute the batter between six cavities of a lined or greased muffin pan, filling each cavity about 2/3 full.
Top each muffin with some rainbow sprinkles if desired.
Bake the muffins for about 22 - 25 minutes, or until a toothpick inserted comes out clean.
Let the muffins cool completely before removing them from the pan.
Dig in and enjoy!