Bring a large pot of water to a boil and cook pasta according to box directions. Strain but reserve 1/4 cup of the pasta water. Set cooked pasta aside.
While your pasta is cooking brown sausage in a pan over medium heat, about 5-7 minutes. Transfer to a colander to strain grease. Set aside.
To the same pan that you cooked the sausage in add olive oil, shallot, garlic, oregano and crushed red pepper. Cook until shallot is translucent, about 5 minutes.
Return sausage to the pan, add cooked pasta, arugula, spinach and reserved pasta water. Toss to combine and cook for 2 minutes or just until the greens wilt. Season to taste with salt and pepper.
Transfer to serving platter, sprinkle with Parmesan cheese. Serve immediately.