Mix vanilla extract, milk, butter, sugar and egg in a microwave safe mug
Optionally you can add nuts or cinnamon or berries to it as per taste
Trim edges of bread slices. Cube them and add to mug. Mix well
Let it sit on counter for 5-7 minutes
Microwave for 1 min 30 sec. Longer you microwave, drier the pudding, its best to keep it little moist
Garnish with chocolate chips and serve warm