Yes, Doubling this Hershey\\s cocoa brownie 8x8 recipe will let you fill a 9x13 baking pan for nice thick, fudgy brownies. Bake for 33-35 minutes. They will appear soft in the middle, but as long as the toothpick comes out clean, remove from the oven. Do not over bake, the brownies will continue to cook while cooling.