Line an 8 inch brownie pan with parchment paper both ways, set aside.
In a stand mixer bowl with beater attachment, add the almond butter, milk, stevia and lemon flavor. Mix on low speed.
In a small bowl, whisk together the protein powder, oat flour and matcha powder. Slowly add this to the mixing stand mixer.
Mix until the mixture is even, scraping down the sides of the bowl if necessary. It should have a texture like cookie dough.
Scoop the mixture into the prepared pan and flatten the surface with a rubber spatula or pastry roller.
Tightly cover the pan with plastic wrap and refrigerate overnight.
The next day, slice the protein bars and drizzle them liberally with chocolate. Serve!
To store, place the protein bars on a plate and wrap tightly.