Pre-heat your oven to 350℉.
Line 12 muffin tin with liners, or grease muffin tin well
In a large sized bowl mix together the Flour, Sugar, Baking powder, Baking soda, Salt and Cinnamon.
In a separate bowl, mix together the Milk, Melted Butter, Vanilla and Egg.
Add the wet ingredients (Gradually) to the large bowl with dry ingredients. Stir this until combined, DO NOT overmix the ingredients.
Fill your muffin tins (3/4 full) with the batter.
Bake in the pre-heated oven for 18-20 minutes. I usually bake for 16 minutes, and check start to check the muffins, you want them golden brown and inserted toothpick comes out clean.
While muffins are baking, in a small bowl mix together the 1/4 cup granulated sugar and the 1 tsp cinnamon sugar.
After the muffins are done baking, allow them to cool for a few minutes. Next you will either dip them into melted butter or spray the tops with spray butter and sprinkle on the cinnamon & sugar mixture.
Enjoy your yummy muffins!