Preheat oven to 325 degrees Fahrenheit. Line muffin pan with liners or heavily grease. Set aside.
In large bowl combine dry ingredients: nut flour, coconut sugar, cassava flour, coconut flour, baking soda and sea salt.
In medium bowl combine wet ingredients: fat of choice, milk, egg and apple cider vinegar.
Add wet ingredients to dry ingredients and stir to combine.
Fold in blueberries.
Fill muffin tin with batter. Bake until toothpick inserted in center comes out clean, about 25-30 minutes for larger muffins.