This simple spaghetti is sweet and creamy, thanks to loads of sliced zucchini that’s cooked until caramelized and silky.
2 pounds zucchini, trimmed and cut into 1/4-inch-thick coins (about 7 cups)
1/4 cup extra-virgin olive oil, divided
1 teaspoon kosher salt, divided
6 ounces uncooked spaghetti
3 tablespoons unsalted butter
2 garlic cloves, thinly sliced (about 1 tablespoon)
2 ounces caciocavallo cheese, provolone piccante, or Fontina, shredded (about 1/2 cup)
1/4 ounce Parmigiano-Reggiano cheese, grated (about 1/4 cup), plus more for garnish
1/4 cup thinly sliced fresh basil, plus small leaves for garnish
Preheat oven to broil with rack 5 inches from heat. Toss together zucchini and 3 tablespoons oil in a bowl. Arrange zucchini coins in a single layer on 2 large rimmed baking sheets. Broil zucchini, 1 pan at a time, until tender and browned, 5 to 10 minutes, flipping halfway through cooking. Sprinkle with 1/4 teaspoon salt. Set aside.
Bring a large pot of salted water to a boil over high. Add spaghetti; cook 1 minute less than package instructions for al dente, about 10 minutes. Drain, reserving 1 1/2 cups pasta cooking liquid; set aside.
Meanwhile, heat remaining 1 tablespoon oil in a large skillet over medium. Reserve 1/4 cup broiled zucchini coins for garnish. Add remaining zucchini coins to skillet; cook, stirring occasionally, until zucchini is softened and some pieces begin to break apart, about 2 minutes. Add butter, garlic, and remaining 3/4 teaspoon salt; cook, stirring often, until garlic is light golden, about 3 minutes.
Add 1/3 cup reserved pasta cooking liquid to skillet; cook over medium, stirring constantly, until liquid is mostly evaporated, about 1 minute. Add cooked spaghetti and 1/3 cup pasta cooking liquid; stir, turning pasta constantly until well coated with zucchini mixture. Remove from heat; add caciocavallo, Parmigiano-Reggiano, sliced basil, and 1/3 cup pasta cooking liquid. Stir constantly until sauce thickens and pasta is evenly coated. (Add additional pasta cooking liquid if needed, 1/4 cup at a time, to thin sauce to desired consistency.)
Garnish pasta with reserved zucchini coins, additional basil leaves, and grated Parmigiano-Reggiano. Serve immediately.
