Mix together flour, cinnamon, sugar, baking soda, and baking powder in mixing bowl. I use my electric mixer.
Add butter (room temperature), egg whites, sour cream, vanilla, and milk - Mix until smooth (no lumps).
Add cupcake liners to cupcake pan.
Combine cinnamon and sugar in a small bowl.
Place 1 tablespoon of batter into each cupcake liner
Sprinkle ¼ teaspoon of cinnamon sugar mixture on top of cupcake batter.
Repeat steps until liners are half way full.
Sprinkle a little more cinnamon sugar mixture on top of half-filled liners
Bake for 16-18 minutes, or until a toothpick comes out with minimal crumbs
Allow to cool for a few minutes
Remove cupcakes and continue cooling on wire rack.
For the Frosting
Mix room temperature butter and shortening until smooth.
Add 1 teaspoon of vanilla, mix until well blended
Add powdered sugar one cup at a time and mix until well blended. (Mixture will be stiff)
Mix in cinnamon until well blended.
Add in milk 1 tablespoon at a time. Add until right consistency.
Pipe cupcakes with frosting.
Sprinkle with cinnamon sugar if desired.
Video
Notes
Wait until cupcakes are completely cool before frosting.This recipe is easily doubled and the frosting recipe is great on other cupcake batters as well!Tip: If you want cupcakes with tall frosting, prepare 2 batches of frosting.