Mix the Egg White Protein into the warm water until it is dissolved.
Add the almond butter and mix well.
Add the allulose, cocoa powder, vanilla extract, and salt and mix until well-combined.
Pour the batter into a greased microwave-safe mug and sprinkle the chocolate chips over the surface if using.
Microwave on full power for 45-60 seconds. (At 45 seconds, the brownie will be fudgier; at 60 seconds it will have a more cake-like texture.)
The mug will be very hot. Let cool slightly before removing from the mug or digging in!