Summer Squash Gratin With Pickled Rye Bread Crumbs
This rustic casserole was first developed using a specialty pickled rye bread from Carissa’s The Bakery in East Hampton, N.Y. The same effect is achieved in this recipe by mixing fresh rye bread crumbs (or even white bread crumbs) with a splash of pickle juice. Summer squash and zucchini are layered with caramelized onions, Gruyère and a handful of the bread crumbs, which help absorb excess moisture. If you can find patty pan squash, it makes for a particularly beautiful presentation.
- Serves: 6 persons
- 2pounds medium zucchini, yellow summer squash or a combination, trimmed
- Kosher salt
- 6tablespoons unsalted butter (3/4 stick)
- 3cups rye bread crumbs (about 8 ounces), preferably from day-old seeded or seedless loaf
- 3tablespoons pickle juice, from a jar of dill pickles
- 1large yellow onion, halved and thinly sliced
- 1tablespoon minced garlic (about 2 large cloves)
- 1teaspoon roughly chopped fresh thyme leaves
- ¼teaspoon red-pepper flakes
- ½teaspoon black pepper
- 1 ½cups grated Gruyère (about 4 ounces)
Step 1Heat the oven to 400 degrees. Slice squash 1/4-inch thick, sprinkle with 2 teaspoons salt, and place in a colander set in the sink for at least 30 minutes and up to 1 hour, tossing occasionally with your hands. Gather the squash in a kitchen towel or paper towel and squeeze gently to remove excess moisture.
Step 2While the squash drains, melt 3 tablespoons butter in a 10-inch cast-iron skillet over medium heat. Add the breadcrumbs, 1 tablespoon pickle juice and 3/4 teaspoon salt. Stir until all the butter is absorbed, transfer to a bowl and set aside. Wipe the skillet clean using a paper towel.
Step 3Heat 1 tablespoon butter in the skillet over medium-low. Add the onions and cook, tossing occasionally, until the onions are lightly caramelized, 15 to 20 minutes. Add the remaining 2 tablespoons pickle juice, the garlic, thyme, red-pepper flakes, pepper and 1/2 teaspoon salt and cook until the garlic is fragrant, about 1 minute. Off the heat, stir in 2 tablespoons butter until melted.
Step 4Add half the squash to the skillet and toss with tongs until combined. Add the rest of the squash and toss again. Add the Gruyère, along with 1/3 of the bread crumbs and toss well. Arrange into one packed layer, sprinkle with the remaining bread crumbs and bake until browned and bubbling, 30 to 35 minutes. Serve hot.