• 2 oz. Pecorino Romano cheese, grated (1 c.)
Heat oil in 12-inch nonstick skillet over medium-high heat until just smoking. Add sausage and cook, breaking up meat into rough 1/2-inch pieces with wooden spoon, until lightly browned, about 5 minutes. Stir in garlic and pepper flakes and cook until fragrant, about 30 seconds.
Meanwhile, bring 4 quarts water to boil in large pot. Add broccoli rabe and 1 tablespoon salt and cook, stirring often, until crisp-tender, about 2 minutes. Using slotted spoon, transfer broccoli rabe to skillet with sausage mixture.
Return water to boil, add pasta and cook, stirring often, until al dente. Reserve 1 cup cooking water, then drain pasta and return it to the pot. Add sausage-broccoli rabe mixture, Pecorino and 1/3 cup reserved cooking water and toss to combine. Adjust consistency with remaining 1/3 cup reserved cooking water. Season with salt and pepper to taste.