In a small mixing bowl, whisk together egg, almond flour, baking powder, sugar-free crystal sweetener, and lemon juice to form a consistent cake batter.
Add in some optional ingredients now, if desired, like lemon zest or blueberries - fresh or frozen.
Transfer the batter into a tall microwave-safe mug. Your mug cake is going to rise and double in height so make sure the mug you use is high enough to avoid the mug cake batter to overflow in the microwave. Don't microwave into 2 mugs or it will impact the microwaving time consequently. Bake all at once and share!
Microwave on high power (800W) for 90 seconds.
Remove from the microwave and cool for 2 minutes before eating and adding any toppings.
Enjoy directly into the mug or unmold on a plate and half the recipe to share!
Preheat oven to 180C (350F)
Place the batter into a medium-size oven ramekin or 2 small ramekins.
Bake for 12-15 minutes. Make sure you check the baking process after 8 minutes and every 2 minutes. Use a skewer that you insert in the center of the mug cake. It is baked when it comes out with no (or very little) crumb on it. Note that if you are using smaller ramekins and half the batter in two ramekins the cakes cook faster between 8-12 minutes.
Microwave baked cakes don't store well, no more than 30 minutes to 1 hour. After that, the texture dries out really fast and you will lose the spongy cake texture. I recommend baking the mug cake if you intend to store it for 2-3 days at room temperature.
Serving sizeThis recipe serves 1 large mug cake (7.4g net carbs) or 2 small mug cake as in the picture, split batter in two and bake/microwave individually, net carbs will be 3.7 grams per mug cakes. Nutrition panelNutrition panel is for one mug cake batter without the blueberries. The whole recipe includes 7.4 g net carb for a large mug cake. If you add 2 tablespoons of blueberry you up the carbs slightly to 9.8 g net carb per serve and 252 calories.