In a bowl, mix oil, egg, water and chocolate cake mix, until just combined. Divide the cake mixture into four 7 oz. cups or two 12 oz. mugs.

Microwave on high for 90 seconds to 2 minutes, watching to make sure it doesn’t spill over (depending on the size of the mug).

Let cool for one minute before eating. Top with graham crackers, chocolate chips and mini marshmallows - optional.

Serve immediately.