Preheat the oven to 350 F/176 C. Set the main rack in the middle position.
Add the egg and the brown sugar in a large bowl and cream together with a hand mixer or wooden spoon.
Mix in the almond milk until well combined.
Combine all the dry ingredients the gluten-free flour mix, flaxseed, baking powder, cinnamon, and nutmeg and mix into the main bowl.
Fold in optional chocolate chips, nuts, coconut flakes, blueberries, etc. if desired. 1/2 to 1 cup worth.
Line a muffin pan with paper cups or spray it with cooking spray. Fill each cup up 2/3 to 3/4 full with batter. Bake on the middle rack for 30 to 35 minutes until a toothpick comes out clean.
Allow the muffins to cool in the pan for a few minutes, then transfer to a wire rack to cool completely. Enjoy!