Add all of dry ingredients to mug.
Mix well with a fork or small whisk until blended.
Add oil and water.
Mix well (add mix-ins if using).
Put in the microwave and cook on high heat for 1 minute 40 seconds - 2 minutes.
Add toppings or a scoop of ice cream and enjoy!
I use Whole Wheat Pastry flour to make it a bit nutritious.
Peanut Butter Swirl: add 1-2 tbsp creamy peanut butter into mix before microwaving, or add 1 tablespoons on top of brownie after its cooked.(I use chunky. Smooth peanut butter doesn't have has much fiber in it compared to chunky)
I tried Nutella till I noticed
S'mores: top cooked brownie with mini marshmallows and graham cracker crumbs