Preheat oven to 350 degrees.
Whisk together flour, sugar, cinnamon, baking soda, and baking powder in a large mixing bowl.
Add butter, egg whites, vanilla, sour cream, and milk and mix on medium speed until smooth.
Combine cinnamon and sugar in a small bowl.
Add cupcake liners to cupcake pan.
Place 1 tablespoon of batter into each cupcake liner, spread evenly.
Sprinkle 1/4 tsp of cinnamon sugar onto the batter.
Repeat steps 6 and 7.
Add one more large tablespoon of batter to each cupcake liner.
Sprinkle a bit of cinnamon sugar on top of each cupcake if you want. Liners should be about half full.
Bake for 16-18 minutes, or until a toothpick comes out with a few crumbs
Allow to cool for 1 minute, then remove to a cooling rack to finish cooling.
To make the icing, beat the shortening and butter until smooth.
Slowly add 3 cups of powdered sugar. Mix until combined.
Mix in the cinnamon, vanilla extract, and 1 tbsp water.
Add the rest of the powdered sugar and mix until smooth. Add more water to get the right consistency, then ice the cupcakes.