In a microwave-safe mug or ramekin, whisk together almond flour, baking powder, cinnamon and sweetener. Add melted butter, pumpkin purée and egg. Mix until fully combined and smooth.
Microwave on high for 60–90 seconds. Start with 60 seconds and check the center. If it's still wet, microwave in 10-second intervals until set. It should be firm but moist.
While the cake cools slightly, mix the cream cheese, sweetener, almond milk, and cinnamon/pumpkin spice in a small bowl until smooth and creamy.
Spoon the frosting over the warm cake and enjoy right away!
