Choose the right mug. Use a microwave-safe mug that holds at least 12 ounces. This gives the batter room to rise without overflowing.

Melt the butter. Add 1 tablespoon butter to the mug and microwave for 15–20 seconds until melted. Swirl it around to lightly coat the sides.

Mix the wet ingredients. Whisk in 1 large egg, 1/2 teaspoon vanilla extract, and 1 tablespoon heavy cream (or almond milk) until smooth.

Add dry ingredients. Stir in 3 tablespoons almond flour, 1/2 teaspoon coconut flour, 1/2 teaspoon baking powder, 1 1/2 to 2 tablespoons granulated keto sweetener, 1 teaspoon cinnamon, and a small pinch of salt. Mix until just combined, with no dry pockets.

Check thickness. The batter should be thick but scoopable. If it seems too thick, add 1 teaspoon more cream or milk. If too thin, add a pinch more almond flour.

Microwave carefully. Cook on high for 60–75 seconds. Start checking at 55 seconds. The top should look set and spring back lightly when touched. Avoid overcooking.

Rest briefly. Let the cake sit for 1 minute. This helps it finish setting and stay moist.

Optional quick frosting. Mix 1 tablespoon softened cream cheese with 1–2 teaspoons powdered keto sweetener, a splash of cream, and a pinch of cinnamon. Spread on top or dollop it in the center.

Serve warm. Enjoy straight from the mug or loosen the edges and flip onto a plate.