When I felt like having some bread pudding while alone, I impulsively came up with this recipe while using a previous microwaved custard pudding recipe that I liked as a reference. I used 1 mug + 1 spoon to make it simple.

To prevent it from overflowing, fill the cup with bread only up to about 90% of the way.
While microwaving, keep your eye on it. If it seems like it is going to gush out, stop heating it. Let it rest and then heat it up again.
The cooking time will differ depending on your microwave, so adjust accordingly. Recipe by Punopuno. Yields enough for 1 mug, about 300 ml.