Preheat oven to 375 degrees F. Spray a light colored muffin tin with nonstick cooking spray and set aside.
Add the flour, cinnamon, sugar, salt, and baking powder to a clean deep bowl. Whisk to combine. Create a well in the center. To the well, add in the milk, eggs and melted butter. Beat with a whisk to break up the eggs, then switch to a rubber spatula or spoon to finish stirring batter together.
Scoop into prepared muffin tin and bake 15-20 minutes or until golden brown.
Remove from oven and cool 15 minutes or until you can handle the muffins comfortably. While muffins are cooling, melt butter and combine granulated sugar with cinnamon.
Dip muffins into melted butter, then cinnamon sugar.
Notes
Storage and Make Ahead
Room temperature: Store in an airtight container for up to 3 days.
Make ahead: Bake the muffins a day in advance, then dip in cinnamon sugar right before serving.
Freezer: Freeze uncoated muffins up to 2 months. Thaw at room temp and dip in butter and cinnamon sugar right before serving.
Reheat: Warm in the microwave for 10 to 12 seconds to bring back that soft, fresh-from-the-oven texture.