Preheat oven to 375° F.
In a medium mixing bowl, mash bananas with a fork and add vanilla extract, egg, milk, maple syrup, and Skyr. Mix together with a whisk, and stir in the peanut butter. Combine with a spatula until smooth and thick, and set aside.
In a large bowl combine flour, flaxseed, baking powder, baking soda, cinnamon and salt using a clean whisk. When mixed completely, cut in coconut oil.
With a clean spatula, fold in the wet banana-egg mixture into the dry flour mixture. Try not to over mix the muffin batter or your muffins will have a drier texture. Mix until no flour pockets remain.
Line a muffin tin with muffin liners. For uniform scoops, use an ice-cream scoop to spoon batter into prepared muffin cups. Bake for 15-16 minutes until a toothpick comes out clean. Let cool before serving.
Flax egg: 1 tablespoon ground flax + 3 tablespoons water mixed in a small bowl and let sit for 15 minutes.
Serving size: 1 muffin Calories: 195 calories, Fat: 10 grams, Saturated fat: 4 grams, Carbohydrates: 25 grams, Sugar: 8.5 grams, Sodium: 220 milligrams, Fiber: 3 grams, Protein: 5.5 grams, Cholesterol: 13 milligrams