I read a recipe a while ago for a chocolate cake made in 3 minutes in the microwave. I did not believe it, really, but I made some changes and tried to adapt the recipe to my taste. So here is my lemon poppy seed cake, ready in 5 minutes. It rises beautifully, more light and airy than the chocolate version.
If you'd like a vanilla cake, replace the poppy seeds and the lemon with 1 teaspoon vanilla extract. If you do not have any buttermilk, you can add a few drops of vinegar to fresh milk to curdle it, or use whole-milk yoghurt as also a substitute for the buttermilk.