Melt the butter in a 6 to 8-ounce mug using the microwave.
1 ½ Tablespoons butter
Add vanilla extract and milk. Stir.
⅛ teaspoon vanilla extract, 1 ½ Tablespoons milk
Add all dry ingredients except chocolate chips. Stir well. Make sure no dry ingredients remain in the bottom of the cup.
⅛ cup all-purpose flour, 1 Tablespoon brown sugar, ⅛ teaspoon baking powder, 1 pinch salt
Add chocolate chips and stir well again.
1 Tablespoon semi sweet chocolate chips
Microwave for 1 minute.
Check for doneness. The cake should spring back when lightly touched and no wet spots should remain. If the cake is not done, microwave for 15 more seconds. Set aside to cool completely
Single Serving Frosting
In a small mixing bowl, mix together until smooth butter, cocoa powder, salt, vanilla and powdered sugar.
1 teaspoon butter, ½ Tablespoon cocoa powder, 1 pinch kosher salt, ⅛ teaspoon vanilla extract, ½ cup powdered sugar
Add a small splash of milk and stir to combine. Add more milk, as needed, to get desired consistency.