01 - Preheat oven to 350°F. Lightly grease a standard 12-cup muffin tin or line with paper liners.
02 - In a large mixing bowl, blend oats, protein powder, ground cinnamon, baking powder, and salt until evenly incorporated.
03 - In a separate bowl, whisk together applesauce, egg, milk, maple syrup or honey, vanilla extract, and melted coconut oil or butter until smooth.
04 - Pour wet ingredients into dry mixture; gently stir until just combined.
05 - Add diced apple to batter and fold in gently to distribute evenly.
06 - Spoon mixture evenly into muffin cups, filling each about three-quarters full.
07 - Transfer to oven and bake for 22 to 25 minutes, or until tops are set and lightly golden.
08 - Let oatmeal cups cool in the pan for 5 minutes, then carefully move to a wire rack to cool completely.