In a large microwave-safe mug, mix flour, sugar, baking powder, and salt.
Stir in milk, oil (or melted butter), and vanilla extract until just combined.
Fold in chocolate chips or sprinkles if using.
Microwave on high for 1 minute. If still gooey in the center, microwave in 10-second intervals until cooked through.
Let cool for a minute before adding syrup or your favorite toppings. Enjoy straight from the mug!