Prepare a mug, ramekin, or small ceramic bowl (microwave safe) with a non-stick baking spray.
MAKE BATTER:
In a small bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
In another small bowl, use a hand mixer to cream together the butter and sugar until light and fluffy.
Add in the egg, 3 tablespoons lemon juice, milk, and zest. Mix everything until well combined.
Scoop the batter into the prepared mug, filling the batter about 1⁄2 of the way full. If it’s too full, there will be an overflow in the microwave.
Top with a few white chocolate chips.
COOK:
Microwave for 90 seconds.
MAKE FROSTING:
With a hand mixer, cream butter, 4 tablespoons powdered sugar, and 2 teaspoons of lemon juice in a small bowl until fluffy.
If the frosting is too soft, add some more powdered sugar until the desired consistency is reached. If the frosting is too stiff, add another teaspoon of lemon juice.
FINISH AND SERVE:
Pipe or spread the frosting onto each cake mug. Serve and enjoy.
Notes
These cakes taste great, just topped with a few extra white chocolate chips or lemon frosting. These cakes are best served warm right out of the microwave.
This recipe will give you 2 cake mugs in a larger mug or ceramic bowl (About 1 1⁄4 cup volume). This will provide you with 3 cake mugs if using a mug that is 1 cup in volume. A ramekin will work for this recipe and will be close to the equivalent of a small mug, about 1 cup in volume.
If preferred, milk can be substituted for the lemon juice in the frosting recipe. This will frost 2 mug cakes.