Stir the oats, stevia, skimmed milk and vanilla extract together in a large serving bowl.
Place in the microwave and cook on full power for 2 minutes.
Remove from the microwave, stir and cook for another 2 minutes.
Remove from the microwave and stir in most of the chopped up chocolate.
Sprinkle a few leftover chocolate pieces on top and extra oats, if using, before serving.