Preheat your oven to 375° F. Grease or line the cups of a muffin tin, set aside.
For the muffin batter: In a large bowl, mix together the protein pancake mix, brown sugar, almond flour, baking powder, salt, and cinnamon until thoroughly combined. Remove ½ tablespoon of this dry mix and sprinkle it over the chopped apples in a small bowl. Toss the apples to coat and set aside until needed.
Whisk the avocado oil, egg, Greek yogurt, milk, and vanilla extract together in a small bowl. Pour into the dry ingredients and mix only until combined. Do NOT over-mix. Fold in the apples.
Fill each muffin tin about ¾ the way full.
For the cinnamon sugar: In a small bowl, stir together the granulated sugar and ¼ teaspoon ground cinnamon. Sprinkle the top of each muffin with the cinnamon sugar.
Bake for 20 to 25 minutes, until golden brown or until a toothpick inserted into the center comes out clean. Allow the muffins to cool before eating.