In a medium bowl, whisk to combine milk, oil, brown sugar, and vanilla extract.
1/4 cup milk, 2 tbsp oil, 2 tbsp light brown sugar, 1/8 teaspoon pure vanilla extract
Add flour, cocoa powder, baking powder and salt and whisk again to combine until batter is mostly smooth and no dry lumps remain.
1/4 cup all-purpose flour, 2 tbsp unsweetened cocoa powder, 1/4 tsp baking powder, pinch salt
Transfer batter to a large microwave safe mug*, and drop a tablespoon of Nutella or peanut butter into the middle of the batter – no need to stir. Top with chocolate chips.
1 tbsp Nutella or peanut butter, 1 tbsp chocolate chips or mini chocolate chips
Place mug cake in the microwave and heat for about 70 seconds.**
Carefully remove from the microwave and serve immediately. Top with whipped cream or a small scoop of ice cream, if desired. Enjoy!
*Mug size: You want your mug to be at least 14 ounces.**Microwave wattage: My microwave is 1500 watts, so you may need to adjust your time to be less or more depending on the wattage of your microwave.