Make the brownie batter first. Start by adding the aquafaba to a large mixing bowl. and whisk it until bubbles form.
1
Add sugar
Add in the sugar and continue whisking for another minute until a thin paste forms.
2
Wet
Melt the chocolate in a microwave. Add the peanut butter, melted chocolate, milk, and vanilla extract and stir until combined.
3
Combine
Add the cocoa powder, flour, and salt then stir to combine just until no more dry flour is visible. Transfer the brownie batter to a prepared baking pan and smooth out to create an even layer. Set aside.
4
Mix
Make the blondie batter next. Add the aquafaba, sugar, peanut butter, and vanilla to a second large mixing bowl. Stir well to combine.
5
Combine
Add the flour, baking powder and salt and stir until just combined. Then fold in the chocolate chunks. The batter will be thicker, more like cookie dough consistency.
6
Bake
Add the blondie batter to the pan on top of the brownie batter and spread out. Swirl the two together if desired. Bake on the center rack for 40-45 minutes at 350F.
7
Serve
Allow to cool in the pan for 10-15 minutes before slicing. I know it's hard to resist, but they continue to set as they cool. If you slice into them too soon they may be too gooey.