To a small microwave-safe bowl, add the granulated sugar, cocoa, water, oil, brown sugar, vanilla, salt, and whisk to combine.
Add the flour and stir until just combined, don’t overmix.
Add the chocolate chips and stir to combine.
Cook on high power in the microwave for about 1 minute, or until the brownie is as set in the center as desired. All microwaves, bowls, ingredients, and preferences for doneness vary, so you will need to experiment with how long it takes to cook given your variables. I recommend stopping to check at the 45-second mark and going from there in 15-second bursts as necessary.
Optionally add ice cream or whipped topping and serve immediately. Brownie is best warm and fresh.