Ingredients:

  • 1 teaspoon Granulated Sugar (for topping)
  • 1/2 teaspoon Ground Cinnamon (for topping)
  • 4 Tablespoons All-Purpose Flour
  • 3 Tablespoons Granulated Sugar
  • 1/4 teaspoon Baking Powder
  • 1/8 teaspoon Cream of Tartar
  • Pinch Fine Sea Salt
  • 2 Tablespoons Unsalted Butter (Melted)
  • 3 Tablespoons Whole Milk
  • 1/2 teaspoon Vanilla Extract

Instructions:

  1. Prepare the Swirl Topping: In a small ramekin, combine the 1 teaspoon of sugar and 1/2 teaspoon of ground cinnamon. Whisk briefly until homogenous. Set aside.
  2. Combine Dry Ingredients: Place the flour, 3 tablespoons of sugar, baking powder, cream of tartar, and salt directly into the large microwave-safe mug. Use a fork or small whisk to thoroughly mix the dry ingredients, ensuring there are no lumps.
  3. Mix the Wet Ingredients: Add the melted butter, whole milk, and vanilla extract to the dry ingredients in the mug. Stir vigorously with a fork until just combined. Do not overmix; a few small pockets of dry mix are acceptable.
  4. Add the Cinnamon Swirl: Spoon approximately two-thirds of the prepared cinnamon-sugar topping mixture onto the batter. Use a fork or a small knife to gently swirl the topping into the batter, performing only 1-2 lazy figure-eights to create ribbons of spice. Sprinkle the remaining one-third of the topping evenly over the surface of the batter.
  5. Microwave and Test for Doneness: Place the mug in the centre of the microwave. Cook on high (assuming 1000W) for 60 seconds. If the centre looks wet or jiggly, return it to the microwave in 10-second increments (maximum of two additional increments).
  6. Rest and Serve: Carefully remove the mug. Allow the cake to cool in the mug for 1 minute—this allows the residual heat to finish cooking the centre and ensures a moist crumb. Serve immediately.