Grease the inside of a ramekin/2 mugs or microwave-safe bowl with melted butter. I used a glass dessert bowl.
For the cake: Mix all dry ingredients - almond flour, sweetener and baking powder - in a separate bowl.
Add all wet ingredients and mix thoroughly with a fork. If you find your dough is too liquid add a bit more almond flour.
Transfer batter into your ramekin/small bowl and level the top.
Microwave on high for ca 90 seconds. You can also bake the cake at 180 Celsius/360 Fahrenheit for ca 15 minutes.
Remove from microwave and turn upside down onto a plate.
For the glaze, melt the butter, then stir in the cream, lemon juice and sweetener.
Let it cool until the glaze begins to thicken but can still be poured. Then spoon/pour over cake and serve.
Video
Notes
If you wish, you could add 1 tsp of poppy seeds.For my UK readers: If you want to use ground almonds, you need to add 1-2 additional tablespoons as ground almonds are coarser than almond flour.