This costume will be such a treat to see.
What you need to do: Make the cupcake wrapper from poster paper stuck on a laundry basket that has its bottom cut out. Hold it up with braces. Use fleece as the icing and hot glue randomly to scrunch it up. Stick pom pom balls on the fleece as the sprinkles. And don't forget to make the cherry hat out of Styrofoam balls (spray painted red) and pipe cleaners.