I use a 12 x 17 sheet pan. If you don't have a large enough pan you can divide the ingredients between two smaller pans.
Since this can be enjoyed as a complete meal without any sides I've settled on a serving size being one third of the sheet pan. If you're really hungry this easily divides into two hearty servings. If children are eating this as well or if you're adding other sides you could potentially get more than three servings.