2 tablespoons olive oil, plus more for drizzling
8 ounces sweet Italian sausage, casings removed
½ medium red onion, finely chopped
¼ cup torn pitted olives, preferably Castelvetrano
1 14-ounce can cherry tomatoes
12 ounces spaghetti
¼ cup peperoncini, thinly sliced
2 ounces Pecorino or Parmesan, finely grated, divided
2 tablespoons unsalted butter
½ cup torn basil
Heat 2 Tbsp. oil in a large skillet over medium-high. Cook sausage, breaking up with a wooden spoon, until cooked through, browned, and crisp in places, 5–8 minutes. Transfer to a small bowl with a slotted spoon. Reduce heat to medium; add onion and olives to skillet. Cook, stirring often, until onion is translucent, about 5 minutes. Add tomatoes, increase heat to medium-high, and cook, mashing tomatoes lightly and stirring often, until juices are slightly thickened, about 3 minutes.
Meanwhile, cook pasta in a large pot of lightly salted boiling water, stirring occasionally, until very al dente, about 6 minutes. Drain, reserving 1 cup pasta cooking liquid.
Add pasta and ¾ cup pasta cooking liquid to sauce and cook, tossing, until pasta is al dente and sauce coats noodles. Mix in peperoncini, cooked sausage, and another ¼ cup pasta cooking liquid. Then, tossing constantly, gradually add all but ½ cup cheese, followed by butter. Once incorporated, remove from heat and mix in basil. Divide pasta among bowls. Drizzle with oil; top with remaining cheese.
via Bon Appétit