This pasta with caramelized onions and sausage combines sweet, slow-cooked onions and crumbled Italian sausage with spiral pasta for a rich, satisfying dinner that’s simple enough for a weeknight.
Bring a large pot of salted water to a boil for the pasta.
Heat 1 tablespoon olive oil in a large skillet over medium heat. Add the sausage and cook until browned, 6 to 8 minutes, breaking it into small crumbles with a wooden spoon.
Transfer the sausage to a bowl and set aside.
Pour off excess fat from the skillet, leaving about 1 tablespoon in the pan. (If there isn’t enough fat remaining, add a little olive oil.) Reduce the heat to medium-low and add the butter, stirring until melted.
Add the sliced onions to the pan and toss to coat with the butter and fat. Cover and cook, stirring occasionally, until the onions soften and begin to release their moisture, 8 to 10 minutes.
Remove the cover, raise the heat to medium, and season the onions lightly with salt, pepper, and a pinch of sugar.
Continue cooking the onions, stirring frequently and scraping up any browned bits from the pan, until they become deep golden and very soft, about 20 minutes. Note: If the onions begin sticking, add 1 to 2 tablespoons of water to loosen them.
Once the onions reach the right consistency, reduce the heat to low and return the cooked sausage to the pan. Stir to combine and keep warm.
Meanwhile, cook the pasta according to package directions until al dente. Drain well.
Add the hot pasta to the skillet with the onion and sausage mixture. Drizzle with 1 to 2 tablespoons olive oil and toss until evenly combined.
Taste and adjust the seasoning with additional salt and pepper as needed.