Ingredients:

  • 4 tbsp (32g) all-purpose flour
  • 2 tbsp (25g) light brown sugar, packed
  • 1/4 tsp (1g) baking powder
  • 1/8 tsp (0.5g) salt
  • 3 tbsp (45ml) whole milk
  • 1 tbsp (14g) unsalted butter, melted
  • 1/4 tsp (1ml) vanilla extract
  • 1 tbsp (12g) light brown sugar
  • 1/2 tsp (1g) ground cinnamon
  • 1 tsp (5g) unsalted butter, softened

Instructions:

  1. Melt 1 tbsp (14g) of butter in a 12 oz microwave-safe ceramic mug in the microwave for 20 seconds.
  2. Add the 2 tbsp (25g) brown sugar, 3 tbsp (45ml) milk, and 1/4 tsp (1ml) vanilla extract directly into the melted butter. Stir until the sugar has mostly dissolved.
  3. Sift in 4 tbsp (32g) flour, 1/4 tsp (1g) baking powder, and 1/8 tsp (0.5g) salt. Whisk gently until the batter is smooth and no dry flour streaks remain; do not overmix.
  4. In a separate small bowl, mash together 1 tbsp (12g) brown sugar, 1/2 tsp (1g) ground cinnamon, and 1 tsp (5g) softened butter until a thick paste forms.
  5. Drop small dollops of the cinnamon paste onto the top of the batter. Use a toothpick or knife to gently swirl the paste into the top 1/2 inch of the batter.
  6. Place the mug in the center of the microwave and cook on high for 60 seconds until the top looks set and matte.
  7. Let the cake rest for 1 minute before eating to allow the internal steam to set the crumb.