In your microwavable mug, mix together the milk, egg, sugar, cinnamon and vanilla until combined
Cut your buttered bread into square bite-sized pieces
Add the bread and raisins to the mug and press them down so they are submerged within the liquid. I like to leave it on the counter for 10 minutes for the bread to soak up the custard
Microwave for roughly 1-1½ minutes. It does take a little longer than my other microwave cakes. I suggest checking it after 1 minute and go from there. The timing is based on my 1200W microwave so yours might vary.