Mix the cupcake batter together. Fill the cupcake wells ¾ full with batter. Bake in a preheated 350 F. degrees oven or (325-degree oven for dark pans) for 20-24 minutes or until the top of a cupcake springs back when touched. Allow cupcakes to cool completely before frosting.
Make the chocolate buttercream frosting. Refrigerate until serving. Fill one piping bag with about ¼ cup of the Chocolate Butter Cream frosting and snip off the point of the bag. Slide the star tip to the bottom of the second piping bag and fill with the remaining frosting. Set aside.
Use a knife to cut a hole in the top of each cupcake the size of a mini cadbury egg. Squeeze a small amount of frosting In the bottom of the hole you cut out in each cupcake with the piping bag without the star tip. Push one unwrapped mini Cadbury Creme Egg into each hole in the cupcake center.
Squeeze another small dot of frosting on top of each Cadbury Creme Egg. Pick up the piece of cake you removed earlier and trim some of the cake off the bottom, leaving a flat cap. Fit it into the hole and press gently but firmly down to secure it to the frosting you placed on top of the candy egg.
Frost each cake with the star tip and decorate with green sprinkles and a Cadbury egg.