Add in flour, sugar, baking powder and salt. Stir until flour is incorporated.
Cinnamon Filling
Mix together brown sugar, cinnamon and melted butter.
Fold half of cinnamon mixture into batter. Don't over stir, you want streaks of cinnamon.
Fill each lined or greased muffin tin with 1/4 of the batter.
Sprinkle the top with remaining cinnamon filling.
Bake at 375 degrees F. for 12-15 minutes.
Cool in pan for a few minutes and then remove to a cooling rack.
Mix together glaze to a nice drizzling consistency.
Drizzle cooled muffins.
Video
Notes
Don't add hot melted butter into your batter, it will cook your egg and melt your sugar. Let the butter cool off before adding it in but don't let it harden back up.
You can substitute the milk for almond milk if you want a dairy free muffin.
Do not use a whole egg in this recipe, you will end up with eggy tasting muffins. I beat an egg and then measure out 1 Tbsp of beaten egg. Save the rest of the egg to make a giant cookie
Accurate measuring is really important for small batch recipes