Balsamic Mushroom and Sausage Pasta

Preparation

1. Step 1

   Cook 12 oz. medium tube pasta in a large pot of boiling salted water, stirring occasionally, until al dente. Drain, reserving 1 cup pasta cooking liquid.

   Step 2

   Meanwhile, heat 2 Tbsp. extra-virgin olive oil and 2 Tbsp. unsalted butter in a large Dutch oven or other heavy pot or skillet over medium-high until butter is melted. Add 1 lb. crimini or button mushrooms, cut into ¼" pieces, and cook, stirring occasionally, until slightly softened, about 2 minutes. Add 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt; cook, stirring occasionally, until liquid is evaporated and mushrooms are browned, 5–7 minutes. Transfer to a small bowl.

   Step 3

   Heat remaining 2 Tbsp. extra-virgin oil in same pot over medium-high. Add 8 oz. hot Italian sausage and ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt. Cook, breaking meat into smaller pieces with a wooden spoon or heatproof rubber spatula, until cooked through, about 2 minutes.

   Step 4

   Add 1 large red onion, finely chopped, and cook, stirring occasionally, until lightly browned, about 5 minutes. Add 4 garlic cloves, coarsely chopped, and cook, stirring often, until combined and fragrant, about 2 minutes. Return mushrooms to pot and add 2 Tbsp. tomato paste and ¼ tsp. crushed red pepper flakes; season with freshly ground black pepper. Cook, stirring often, until paste is darkened in color, about 2 minutes. Pour in ⅓ cup balsamic vinegar and cook, scraping up any browned bits stuck to bottom of pot, 30 seconds.

   Step 5

   Reduce heat to medium. Add pasta, ½ cup reserved pasta cooking liquid, and remaining 2 Tbsp. unsalted butter. Cook, stirring often and adding more pasta cooking liquid a little at a time if needed, until pasta is coated and sauce is glossy, about 30 seconds.

   Step 6

   Transfer pasta to a platter; top with finely grated Parmesan.