Slab pie is essentially an enormous, shallow, rectangular pie made in an 18 by 13-inch rimmed baking sheet. Since it serves up to 20—more than twice the amount as a regular 9-inch pie—it’s great for feeding a crowd. Cutting it into squares makes for neat serving.
This is what a traditional peach pie looks like—beautiful, right? It's about 9 inches in diameter and can serve 8 to 10 people. But that's if you're cutting it very carefully. It's definitely not designed for a crowd.
This peach pie is made in a sheet pan. It has all the things you love about a traditional peach pie—flaky crust; sweet, juicy fruit filling; attractive lattice crust—but it can serve up to 24 people. In almost the same amount of time it would take you to make a traditional pie, you have pie for a crowd.