1. Beat first 5 ingredients at low speed with an electric mixer just until dry ingredients are moistened. Increase speed to medium, and beat 3 to 4 minutes or until smooth, stopping to scrape bowl as needed.
2. Place paper baking cups in muffin pans, and coat with cooking spray; spoon batter evenly into baking cups, filling each two-thirds full.
3. Bake at 350° for 25 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on wire racks 10 minutes; remove cupcakes from pans to wire racks, and cool 1 hour or until completely cool.
4. Prepare Chocolate Buttercream as directed, stirring in 1/4 cup finely chopped thin crème de menthe chocolate mints. Spread cupcakes evenly with Chocolate Buttercream. Garnish with shaved or chopped thin crème de menthe chocolate mints, if desired.
Note: For testing purposes only, we used Andes Creme de Menthe Thins.