Preheat oven to 375 degrees.
Spray muffin pan with cooking spray, or use paper liners.
Mix flours, sugar, baking powder, baking soda, xanthan gum, salt, and nutmeg in large mixing bowl. Add blueberries; stir to coat evenly.
Add milk, oil, flax meal and vanilla. Stir until just blended.
Fill muffin pans 2/3 full. Sprinkle top with cinnamon sugar.
Bake 20 minutes until lightly golden.