01 - Preheat oven to 350°F. Lightly grease a standard 12-cup muffin tin or line each cup with paper liners.
02 - In a large mixing bowl, thoroughly combine rolled oats, vanilla protein powder, ground cinnamon, baking powder, and salt.
03 - In a separate mixing bowl, whisk applesauce, egg, milk, maple syrup or honey, vanilla extract, and melted coconut oil or unsalted butter until fully blended.
04 - Pour wet ingredients into the dry ingredients and stir gently until just incorporated.
05 - Fold the diced apple into the combined batter.
06 - Evenly distribute the batter into the prepared muffin cups, filling each approximately three-quarters full.
07 - Place muffin tin in the oven and bake for 22 to 25 minutes, or until tops are set and lightly golden.
08 - Allow oatmeal cups to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.