• Preheat oven to 350F degrees. Spray two 9-on. round baking pans with non-stick cooking spray. Set aside.
• In a medium bowl, mix flour, baking powder, baking soda, salt and ground cinnamon. Set aside.
• In a large bowl, using an electric or stand mixer on medium speed, beat eggs and sugar for about 2 minutes, or until light and creamy. Add the butter and vanilla extract and beat on low speed for about 1 minute, or until well blended. Beat in the dry ingredients on low speed until blended. DO NOT OVER MIX! Add the sour cream and beat until smooth.
• Divide batter evenly into prepared baking pans. Bake 30 to 35 minutes or until toothpick inserted in center comes out clean. Allow cake to cool before frosting.

MAKE THE FROSTING:

• Mix softened butter on medium speed with an electric or stand mixer. Beat for 30 seconds until smooth and creamy.
• Add powdered sugar, milk, ground cinnamon and vanilla extract. Increase to high speed and beat for 3 minutes or until smooth.
• Spread the frosting between layers and over top and sides of cake. Sprinkle with cinnamon-sugar.