To prepare a surfer squares cookie recipe, first you need to prepare your ingredients. First, you'll need your flour, baking powder, sugar, salt, and cocoa powder. Then, add your wet ingredients to the dry ingredients and mix them together until they're well combined. Next, preheat your oven to 375 degrees F (190 degrees C) and grease two 9-inch square baking pans with non-stick cooking spray. Set aside. Using an electric mixer, beat the butter and sugar on medium speed until light and fluffy, about 2 minutes. Gradually add the egg and vanilla, beating well after each addition. Scoop the batter into the prepared pan and spread it evenly. Bake the cookies for 12 to 15 minutes, or until the edges are golden brown and the center is set.