In a 14 oz. mug, add in the butter. Place into the microwave for 30 seconds.
Add in the vanilla extract, sugar, flour, baking powder, cinnamon, cornstarch, milk, and cinnamon chips.
Stir until the mixture comes together and most of the lumps are gone.
Place into the microwave for 1 minute 30 seconds to 1 minute 45 seconds. I've had the best luck with 1 minute 45 seconds.
Let cool for a minute or two.
Grab a spoon and enjoy!
Reserve a spoonful of cinnamon chips and sprinkle on the top of the batter just before microwaving. This will ensure that cinnamon chips will be at the top of the cake.The mug cake is best consumed within an hour of microwaving.