In a mug, using a fork whisk together the fat, milk and egg. Mix in the dry ingredients till well combined and there are no lumps. Stir in 1 rounded teaspoon of lemon curd.
On a high heat (800w) bake in the microwave for 1 minute and 40 seconds till firm to the touch. Stop the baking for a second or two if it starts to overflow, then restart.
In a small cup, mix together the remaining lemon curd and 2 teaspoons hot water till smooth. Pour the glaze over the still warm cake.
Use a largish mug with straight sides. You could pick the cake a few times with a fork before pouring the glaze over. You can also add 1/4 teaspoon of vanilla sugar to the mixture for a hint of vanilla flavour.