Prepare chocolate cupcakes according to directions. Allow to cool completely before decorating.
In a large bowl, beat together butter, icing sugar, cocoa powder and 1 tablespoon milk. Start on low and gradually increase to high. Add more milk one tablespoon at a time (you may not need to) until ingredients are smooth and well combined. The buttercream should form semi-stiff peaks.
Add red gel food coloring and beat with electric mixer until the color is completely incorporated into the frosting.
Scoop buttercream into a piping bag with Wilton tip #21 attached.
Start out by piping out one circle on the center of each cupcake, about ½ an inch in diameter.
To complete the cupcakes, pipe out 5 more flower/rose circles around the center flower.
Attach Wilton tip #101 on green decorating frosting. Pipe out 3-4 leaves on each cupcake.
Serve!