Spray or rub the inside of a microwave-safe mug with cooking oil.
Mix the almond flour and baking powder in a small bowl. Add butter, egg, and vanilla. Stir with a fork to combine and form a batter. (*See note if using coconut flour and the mixture is thick)
Pour the batter into the mug.
Combine the granulated sweetener and cinnamon in a bowl. Sprinkle over the top of the batter in the mug. Use a knife or chopstick to swirl the topping into the batter, without stirring it up.
Microwave for 60 seconds. Cake should be spongy and cooked through. If not, microwave for another 10 seconds.
To make the glaze, mix the softened cream cheese with the butter and powdered sweetener until smooth. Microwave for 10 seconds to heat it. Pour over the mug cake and serve.
