Grab your favorite mug. It should hold at least 10 - 12 oz. (300 - 360 ml) of liquid.
Place the butter in the mug. Microwave the butter until melted, about 30 seconds in the microwave.
2 tablespoons (28 g) unsalted butter
Stir or whisk in the milk followed by the brown sugar, vanilla extract, salt and baking powder until smooth and well combined. Stir in the flour until smooth and well combined. Stir in or top the brown sugar cake with the chocolate chips.
3 tablespoons (45 ml) milk, 2 tablespoons (25 g) brown sugar, 1 teaspoon (5 ml) vanilla extract , ⅛ teaspoon salt , ¼ teaspoon baking powder, ¼ cup (30 g) all purpose flour, 2 - 3 tablespoons (20 - 30 g) semi sweet chocolate chips
Microwave the mug cake vanilla cake in the microwave for 60 - 90 seconds (1 - 1 ½ minutes). The mixture should puff up and resemble cake. If there is any liquid at the bottom or the cake seems underbaked, heat the mug cake in the microwave in additional 15 second increments until the cake is to your desired consistency.
Allow the mug cake to cool for 2 - 3 minutes. Top the cooled chocolate chip muffin mug cake with more chocolate chips and ice cream if you like and enjoy.