Gather all ingredients: egg, almond flour, coconut flour, erythritol, baking powder, cinnamon, butter, almond milk, cream cheese, and optional syrup.

Mix the dry ingredients in a mug: egg, almond flour, coconut flour, erythritol, baking powder, and cinnamon.

Melt butter and add it to the dry mix along with almond milk, stirring until a smooth batter forms.

Blend cream cheese with remaining erythritol and cinnamon in a bowl to make the swirl.

Layer half the batter in the mug, top with cream cheese mixture, then add remaining batter and swirl.

Microwave for 60 to 90 seconds, checking for a set yet moist texture.

Cool for 1 minute and serve, optionally topped with syrup or whipped cream.