In a small bowl, mix 1 tablespoon of brown sugar, ½ teaspoon of cinnamon powder and ½ teaspoon of melted butter. Stir well to make a sweet cinnamon mix and set aside in a large microwave safe mug.
Add 4 tablespoons of flour, 2 tablespoons of sugar, ¼ teaspoon of baking powder and a pinch of salt. Give everything a quick stir to evenly mix the dry ingredients.
Pour in 3 tablespoons of milk, 1 tablespoon of vegetable oil or melted butter, and ½ teaspoon of vanilla extract. Stir until smooth, making sure there are no lumps.
Drop the cinnamon sugar mixture into the batter and gently swirl it around with a toothpick.
Microwave the mug cake for 60-75 seconds, depending on your microwave.
In a small bowl, mix 1 tablespoon of powdered sugar with 1 teaspoon of milk to make a quick glaze. Drizzle the glaze over the warm cake.
