Are you looking to use up a giant pile of zucchini or summer squash? Say, four pounds of it? This recipe is just the ticket. It’s a simple yet flavor-packed vegetarian gratin, made up of squash slices layered with tomato-pepper sauce and Parmesan cheese, then topped with oil-slicked breadcrumbs. This is what I think of as summer comfort food: crisp and golden on top, bright and fresh-flavored underneath. Plus there’s cheese.
The real secret sauce of this gratin is…well, the sauce. It is one of those simple-yet-spectacular marvels of summer cooking: tomatoes and red bell peppers, simmered with a splash of water until they’re very soft, then blended with a knob of butter and a handful of fresh basil leaves. (You could use olive oil instead of butter, or a mix of the two.) Somehow, those few ingredients produce a rich orange-red sauce that’s creamy-without-cream and packed with bright flavor.
Of course, the sauce is outrageously delicious in this gratin. Tomato, pepper, squash, and basil is a can’t-fail flavor combination. But once you taste this stuff, you’ll want to make extra next time. It’s fabulous over pasta or as a marinara-like dip, and I can only imagine how great it’d be draped over chicken Parmesan. It also freezes beautifully, so you could double the batch while prepping this gratin and save the leftovers for another day.
I tweaked this from a Food52 recipe, which calls for roasting the squash before assembling the gratin. I don’t own enough baking sheets to fit four pounds of sliced squash in a single layer, and I didn’t love the idea of shuffling baking sheets in and out of a very hot oven during the height of summer. So I skip the roasting step altogether, and I don’t really miss it. The flavor of the squash is fresher, and the slices stay firmer and more intact. (A lot of folks–myself included–are averse to the mushiness of fully-cooked zucchini, so I slice my squash on the thicker side for a crisp-tender final texture.)
The roasting step does serve one important purpose, however. It drives off excess liquid from the squash, which would otherwise make the gratin soggy. My solution is to salt-purge the squash instead. After slicing the squash, I toss it with a generous dose of kosher salt, then let it drain in a colander until it softens and gives up a shocking amount of liquid. Then I pat the squash dry, and it’s ready to be layered with sauce and blanketed with breadcrumbs.