You Will Need
Preheat oven to 175°C/350°F.
Mix the sugar, cinnamon and cocoa powder in a small bowl for the layer inside the cupcake.
Whisk together flour, sugar, cinnamon, baking soda and baking powder in a large mixing bowl.
In a separate bowl, whisk the egg whites till stiff peaks form. While still whisking add the vanilla extract slowly, then the sour cream, the butter, a little at a time and finally the milk. Whisk till smooth.
Add the egg white mix to the flour mix and mix till you get a smooth batter.
Place one tablespoon of the batter into each of your cupcake liner, then sprinkle the cinnamon, cocoa sugar covering the whole surface. Then add another tablespoon of the batter. Sprinkle a teeny bit of the cinnamon cocoa sugar on top. (My cupcake liners were pretty small, if yours are a little bigger you can add another layer.)
Bake for 16-18 minutes, or until a toothpick comes out with a few crumbs.
allow to cool completely on a cooling rack.
to prepare the frosting
Whisk the butter till smooth. Slowly add the powdered sugar. Mix in the cinnamon, vanilla extract and milk.
Pour into a piping bag and decorate as you desire. Sprinkle with a little extra cinnamon or cocoa powder.