To prepare a chewy whole wheat peanut butter brownies recipe, first you need to prepare your ingredients. First, you'll need your flour, sugar, cocoa, baking powder, salt, and vanilla extract. Then, add your wet ingredients to the dry ingredients and mix until everything is well combined. Next, preheat your oven to 350?F (180?C) and grease and flour two 9x9x2-inch baking pans. Now, in the bowl of an electric mixer, cream together the butter and sugar until light and fluffy, then add the vanilla and beat until the mixture is fluffy and light in color, about 2 minutes. Add the flour mixture and stir until it's completely incorporated. Pour the batter into the prepared pan and bake for 20 to 25 minutes, or until they're set and the tops are golden brown. Remove from the oven and let cool for 5 minutes before cutting into squares and serving.