In a large pot, bring water to a rolling boil over high heat. Add a generous amount of salt, then stir in the penne rigate pasta. Cook according to package instructions for about 10-12 minutes until al dente.

With 3-4 minutes left, add the broccoli florets into the pot. Cook until bright green and tender, about 3-4 minutes.

Reserve 1 cup of starchy pasta water and drain the mixture, then set aside.

In a large skillet over medium heat, melt the butter until it bubbles. Add the ground Italian sausage, breaking it up as it cooks for 6-8 minutes until browned.

Once browned, stir in the minced garlic and red pepper flakes. Sauté for 1-2 minutes until fragrant.

Add the drained pasta and broccoli mixture to the skillet. Pour in the reserved pasta water, stirring to combine.

Sprinkle in the grated parmesan cheese, stirring until everything is creamy and evenly coated. Adjust seasoning with salt and black pepper to taste.

Serve hot, garnished with additional parmesan cheese, salt, and black pepper if desired.