Add in the dry ingredients (everything except the blueberries). Mix well. The batter will get lumpy before it gets smooth; just keep mixing!
Fold in the blueberries.
Spoon into two large silicone muffin cups.
Bake for 25-35 minutes, or until a toothpick comes out clean and the muffins are firm to the touch.
Enjoy!
Notes
A note about substitutions: because each type of protein powder has a distinct flavor and texture when baked, I would not try substituting different types of protein powders in this recipe.