Preheat oven to 350 degrees. Line a 13 x 9 cake pan with parchment paper. Extend the parchment paper over the sides of the pan so it acts as "handles" when the brownies are done
In a large mixing bowl whisk together erythritol, stevia, almond flour, garbanzo flour, vital wheat gluten, baking powder and cocoa until fully combined.
In a large mixer bowl combine butter, eggs, and vanilla extract. Add dry ingredients to wet ingredients
Beat on low 30 seconds then on medium for 2 minutes. Let batter sit for 2 minutes or until the batter is slightly thick.
Spread batter evenly into the prepared cake pan. Bake for 30-40 minutes or until a tester comes out clean.