01 - Combine cottage cheese, egg, milk, and vanilla extract in a blender or food processor. Blend until completely smooth and creamy.
02 - In a 10–12 oz microwave-safe mug, whisk together oat flour, protein powder, baking powder, cinnamon, sweetener, and salt until evenly distributed.
03 - Pour the blended wet mixture into the mug with dry ingredients. Stir vigorously until fully combined and no dry pockets remain.
04 - In a small bowl, mix melted butter, cinnamon, and brown sugar until well combined.
05 - Drizzle or dollop the cinnamon mixture into the mug batter. Gently swirl with a knife or skewer to create marbled effect.
06 - Microwave on high power for 1 minute 30 seconds to 2 minutes, or until cake is set and springs back lightly to touch. Check at 90 seconds as microwave power varies.
07 - If using icing, whisk together softened cream cheese, milk, vanilla extract, and powdered sugar until smooth and drizzleable.
08 - Drizzle icing over warm mug cake and serve immediately for best texture.