Add the flour, packets Splenda Sweetener, baking powder, and sprinkles to a standard microwave safe mug. Stir until everything is well combined.
Add the milk, vegetable oil spread, and vanilla extract to the mug. Stir until a soft batter forms. Make sure to scrape all the flour out of the corners of the mug.
Microwave for about 60 seconds, or until it has puffed to about 2 times the volume. Cook time will vary with the wattage of your microwave.
Allow the mug cake to cool for a few minutes and enjoy.