1. Preheat oven to 350 degrees and line pans with green greaseproof cupcake liners.

2. In a large bowl, combine cake mix, oil, eggs, milk and sour cream. Stir until combined well.

3. Fill cupcake liners 3/4 full and bake for 15-20 minutes or until an inserted knife comes out clean.

4. Let cool.

5. Chocolate Frosting: Beat butter until smooth. Add cocoa powder, milk and 2 cups powdered sugar. Slowly add in more powdered sugar until you reach your desired consistency. Add more milk if it becomes too thick.

6. Frost cooled cupcakes and then flatten out with a knife (see photos). Pour sprinkles into a shallow bowl or plate and turn frosted cupcake upside down into the bowl to coat with sprinkles. Use the colored paper to make eyes, a mouth and eyebrows. Hot glue Rolos on to the sides as "bolts."