Preheat your oven to 375° F. Grease or line the cups of a muffin tin, set aside.
In a large bowl, whisk together the pancake mix, brown sugar, almond flour, baking powder, salt, and cinnamon until thoroughly combined. Set aside until needed.
In a large bowl or bowl of a standing mixer with the paddle attachment, beat the bananas until softened, about 2 minutes. In a separate small bowl, whisk the avocado oil, egg, and vanilla extract together. Pour over the bananas and whisk just until combined. Add the milk, whisk until incorporated.
Pour into the dry ingredients and mix only until combined. Do NOT over-mix. Stir in the walnuts.
Fill each muffin tin about ¾ the way full. Sprinkle each muffin with granulated 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.
Store in an airtight container at room temperature for a few days, or in the refrigerator for up to one week.