Step 1

Heat oil in a large nonstick skillet over medium-high heat. Add sausage; cook, stirring, until no longer pink, 2 to 4 minutes. Transfer to a plate.

Step 2

Add bell pepper and onion to the pan; cook, stirring occasionally, until softened, about 5 minutes. Stir in kale, garlic, crushed red pepper (if using), and the sausage; cook, stirring, until the kale is wilted, about 3 minutes.

Step 3

Stir in water and pasta; bring to a boil, stirring occasionally. Reduce heat to medium-low, cover, and cook until the pasta is tender, 8 to 10 minutes. Sprinkle with Parmesan and serve immediately.