In a medium-sized bowl, whisk together the protein powder, oat or almond flour, baking powder, ground cinnamon, and a pinch of salt.

In another bowl, beat the egg until frothy, then stir in the almond milk, maple syrup, and vanilla extract.

Carefully fold the wet mixture into the dry ingredients until no large lumps remain.

In a small bowl, mix the coconut oil or melted butter, brown sugar, and additional ground cinnamon until it’s a lovely paste.

Pour half of the batter into a microwave-safe mug. Add half of the cinnamon mixture and swirl it with a toothpick or knife. Pour in the remaining batter and repeat.

Microwave on high for about 1 to 1.5 minutes, or until the cake springs back when touched.

In a small bowl, mix Greek yogurt, softened cream cheese, and maple syrup or powdered sugar for a creamy frosting.

Let your mug cake cool slightly, then top it with the luscious frosting and serve.