Step 1

In a small bowl, mix together all dry cake ingredients with a fork. Add in wet ingredients, stirring until combined. Heavily grease three large mugs* and evenly distribute batter into mugs (~1/2 cup of batter each).

Step 2

Microwave each mug by itself for 1 minute on high. Remove from microwave and shake slightly to loosen cake from mug. Flip mug over onto parchment paper-lined plate or board. The cake should drop right out. Repeat with remaining mugs, then place into freezer for 5 minutes, or until the cakes cool to room temperature.

Step 3

While the cakes are cooling, make the frosting. Combine all ingredients in a standing mixer and beat on high until light and fluffy, about 1 minute. Remove cakes from freezer and frost the top of each layer before stacking.

Step 4

Melt the chocolate and milk in a microwave-safe bowl until melted (about 15 seconds). Drizzle over cake!