Heat 2 tablespoons oil in a large nonstick skillet over medium heat. Add the sausage. Cook, breaking up the meat using a wooden spoon, until browned, about 5 minutes. Scrape the mixture into a bowl. Add 2 tablespoons oil, the broccoli, peppers, and garlic to the skillet and season with salt and pepper. Cook, stirring often, until they soften and begin to brown, about 8 minutes.
1/4 cup extra-virgin olive oil, 1 pound Italian pork sausage, 1 pound broccoli, 2 medium bell peppers, 3 cloves garlic, salt and pepper
Meanwhile, cook the pasta in a large pot of boiling salted water. Reserve 1 cup cooking water and drain the pasta. Return the pasta and reserved water to the pot over low heat. Add the broccoli mixture, cooked sausage, 1/2 cup Parmesan, the lemon juice, and red pepper flakes and stir until liquid is slightly thickened and saucy, about 2 minutes.
1 pound rigatoni, 1/2 cup grated Parmesan cheese, 2 Tbsp fresh lemon juice, 1/2 tsp red pepper flakes