In a medium bowl, combine the BakeGood Brown Sweetener, flour, cocoa powder and salt with the melted butter and water until smooth.
Pour the batter into a microwave safe mug (at least 8oz).
Microwave on high 50-60 seconds until batter puffs up (do not microwave longer than 90 seconds). The brownie is done when the edges are set. The center may appear a little wet on top – this is perfectly normal, do not add additional baking time.
Microwaves all vary slightly in terms of power. Baking time is an approximation but 50-60 seconds generally works well for all models. Do not microwave for more than 90 seconds.