Chocolate Thin Mint Cupcakes

From 6 Bittersweets
Adapted from Trophy Cupcakes via For the Love of Design
Makes 12 to 13 cupcakes

XIAOLU'S NOTES: Only make the ganache after you've frosted the cupcakes since the ganache will need to be used immediately. Cupcakes may be stored in an airtight container for up to 2 days. This recipe could definitely be doubled successfully, since I scaled it down from a recipe from 2 dozen cupcakes.

1 cup sugar
3/4 cup PLUS 2 Tbsp all purpose flour
6 1/2 Tbsp unsweetened Dutch-process cocoa powder
3/4 tsp baking powder
3/4 tsp baking soda
1/2 tsp salt
1 large egg, room temperature
1/2 cup milk [NOT skim]
1/4 cup vegetable oil
1 tsp pure vanilla extract
1/2 cup boiling water

Mint Buttercream (Recipe Below)
Mint Chocolate Ganache (Recipe Below)

Heat oven to 350 degrees F. Grease tops of a cupcake pan and then line it with baking liners.

In a large bowl, sift together sugar, flour, cocoa, baking powder, baking soda and salt. Add egg, milk, oil and vanilla; beat on medium speed for about 2 minutes. Stir in boiling water (batter will be thin). Pour batter into prepared cupcake liners, filling no more than 3/4 full. Bake 20 to 25 minutes or until a toothpick or thin knife inserted into the center of one comes out clean. Cool 5 minutes, then remove from pans to wire racks to finish cooling.

Once cakes are completely cool, place all but 1/4 to 1/3 cup of buttercream in pastry bag fitted with any long and skinny tip that's good for filling. Insert tip into the center of the cupcake and almost to the bottom. Fill each cupcake with 1 to 2 tablespoons of buttercream. Be careful not to overfill, as the top of the cupcake may come off. Alternately, you may cut a cone out of the top of each cupcake and fill with buttercream (an apple corer works well too). Try to make the top of the buttercream level with the cupcake so that there is a smooth top. Cover and chill the reserved buttercream for piping on as decoration at the end. [Make the ganache at this point.]

Dip each cupcake upside-down into the ganache up to the liner, lift cake out of chocolate, and let excess ganache drip off. Next, turn cupcake right-side up and place on wire rack to let ganache set (about 1 hour). (If ganache begins to harden before all of the cupcakes are dipped you may heat for 5-second intervals in a microwave until chocolate is smooth again).

Once ganache is completely set, take the leftover buttercream out of the fridge. Stir to smooth it out. If too stiff to pipe, let sit at room temperature until it softens a little. Transfer to a piping bag fitted with a small round tip or a small plastic zipper-lock bag. If using a zipper-lock bag, snip off a small corner of the bag. To make a shamrock design like this on top of each cupcake, start by piping 4 clover leaves by squeezing straight down to form 4 circular blobs. Then pipe a stem from between 2 leaves. You could also pipe a flower or any other desired pattern or message on top. Enjoy!

Mint Buttercream
1/2 cup (1 stick) unsalted butter, room temperature
1 cup powdered sugar, sifted
1 tsp mint extract
Pinch of salt
Drop of green food coloring (optional)

Cream butter using an electric mixer. When butter is soft and fluffy, start adding sifted powdered sugar a little at a time. When all of the sugar is incorporated, add salt, and mint extract. Add food coloring, if using. Beat until creamy.

Mint Chocolate Ganache
3 oz. bittersweet chocolate (chips or finely chopped bar)
1/3 cup heavy cream
1 tsp unsalted butter
3/4 tsp mint extract

Make ganache after you fill the cupcakes with buttercream. Place chocolate in a medium to large bowl. Bring heavy cream, butter, and mint extract just to a boil. Pour hot cream mixture over chocolate and let sit for about 5 minutes. Begin stirring mixture and continue stirring until the mixture is uniform and smooth (may take about 5 minutes of stirring). Use immediately.