Preheat over to 375°F. Line bottom and sides of 8×8-inch square baking pan with baking paper. Leave paper two inches over the rim. It will help you lift the bars once baked.
mix melted butter, sugar, and vanilla in medium bowl, Add flour, almond flour, cocoa powder and salt and stir until incorporated. Transfer dough to your prepared pan, press the dough evenly across the bottom of the pan. Prick crust with a fork to prevent from puffing up. Bake the crust until golden, about 18 minutes ,Transfer crust to rack and cool in pan.