Making a brownie in a mug is really simple. A little brown sugar, flour, milk, cocoa powder, vegetable oil, and vanilla come together in an 8-ounce mug that's cooked in the microwave for 2 minutes.
Lightly spray the inside of the mug with cooking spray.
Add all ingredients except the chocolate chips to a microwave-safe 8-ounce mug, and stir to combine.
Microwave (uncovered) on high power for 60 seconds. Check it to see if it looks super gooey; if so, microwave in 10 second intervals for up to 20 seconds more. (The top should still look a touch wet in spots when it’s done; it will set as it cools.)
Let it sit for 2 minutes, then sprinkle on the chocolate chips.
Serve warm, topped with vanilla ice cream if desired.
Notes
If you don’t have an 8-ounce mug, a 6-ounce mug will also work well for this recipe.
You can use vegetable oil, or any neutral-flavored oil you like. Or you can use unsalted butter, just melt it before mixing together the brownie batter.
For extra gooey bits of chocolate, double the amount of chocolate chips and stir half into the batter.
For a richer, more deep chocolate flavor, add 1/8 teaspoon espresso powder. You can’t taste the espresso, it just pulls out the flavor of the chocolate.