In medium size bowl, whisk together dry ingredients: almond flour, coconut flour, baking powder, salt, xanthan gum.
In a separate medium size bowl, beat softened butter until smooth (1-2 minutes); add granulated and confectioner swerve and beat with butter until smooth. Add eggs, almond milk, and vanilla... continue beating until well combined.
Add dry ingredients to wet ingredients and beat until batter is smooth.
Fold in frozen blueberries.
Recommend using cupcake liners with muffin tin for baking- bake at 350 degrees for 26 minutes.