Preheat oven to 350 F
Prepare cake mix according to instructions substituting half of the called for liquid with brewed coffee. If your cake mix calls for 1 cup of water use 1/2 cup of water and 1/2 cup of coffee in its place.
Scoop batter into cupcake pan and bake for 20-25 minutes or until golden brown.
Remove from oven and allow to cool.Coffee Buttercream
In a mixer beat together butter, sugar, and vanilla. Add in the brewed coffee 1 TBSP at a time until buttercream is at the desired consistency.
Pipe buttercream on top of cooled cupcakes and dust with some cinnamon if desired.