Add cake ingredients to an 8oz ramekin or microwave-safe mug and whisk until there are no lumps remaining in the batter.
To make the cinnamon swirl, stir together 1/2TB melted butter, 1/4 teaspoon cinnamon, and 1 1/2 TB brown sugar in a small bowl.
Pour the cinnamon swirl mixture on top of the cake batter. Fold the cinnamon mixture into the cake with a butter knife, using a swirling motion.
Microwave cake for 1 minute, or until the center of the cake is cooked through.
Frosting Directions
Add butter and cream cheese to a microwave safe bowl. Heat for 10 seconds, then stir in 4 Tablespoons of powdered sugar, until smooth and creamy. If needed, stir in more powdered sugar to thicken.
You can frost the cooked cake by spooning on half of the frosting and spreading, or you can scoop the frosting into a decorating bag and creating a swirl pattern like what is pictured.
Notes
Nutrition values are an estimate only and will vary based on exact ingredients used and serving size.