Easy and unfussy, this peanut butter chocolate sheet cake is comfort food in a casserole dish. Sheet cakes are great for a crowd, or dessert for a few days! We don’t bake nearly enough sheet cakes, darlings. A sheet cake, like this peanut butter chocolate sheet cake, can be overlooked when we bake for the ‘gram. Or whatever your preferred social media. But sheet cakes are comforting, one of those…