Add cake ingredients to an 8 oz ramekin or microwave-safe mug. Stir well to incorporate and remove any lumps in the batter.
For the cinnamon swirl, add ½ tablespoon butter to a small bowl. Microwave for a few seconds until melted. Add cinnamon and brown sugar. Stir to combine.
Pour cinnamon swirl mixture over the cake batter. Use a butter knife to fold the mixture into the cake, using a swirling motion.
Microwave cake for 1 minute or until the center of the cake is cooked through. Allow cake to cool.
For the cream cheese frosting, add butter and cream cheese to a small bowl. Microwave at 50% power for 10 seconds. Add 4 tablespoons powdered sugar, stir until smooth. Add up to an additional tablespoon of powdered sugar or until desired consistency is reached.
Frost cake by simply spooning on desired amount or by creating the swirl pattern as shown in the photos. To do this, transfer cream cheese frosting to a small sandwich bag, cut off a corner of the bag and pipe the frosting into a swirl starting in the center of the cake.
Notes
Frosting: The frosting recipe included yields enough for two servings if using the swirl frosting pattern shown. Therefore, create two servings by simply replicating the cake making process, but keep the frosting the same.
Use Mug as Mold: If you want to this on a plate rather than out of a mug, make sure to coat the mug with cooking spray before adding the dough.