Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente. Drain and set aside.
While the pasta is cooking, heat the olive oil in a large skillet over medium heat. Add the sausage, breaking it apart with a spoon, and cook until browned and no longer pink, about 5-7 minutes.
Remove the sausage with a slotted spoon and set aside. In the same skillet, add the Romanesco broccoli florets and sauté for about 5 minutes, or until they start to soften.
Add the minced garlic to the skillet with the broccoli and sauté for an additional minute until fragrant.
Pour in the chicken broth to deglaze the pan, scraping up any browned bits from the bottom. Allow to simmer for 3 minutes, reducing the broth slightly.
Stir in the heavy cream and bring the mixture to a gentle simmer. Let it cook for about 5 minutes, until the sauce starts to thicken.
Return the cooked sausage to the skillet and mix well. Season with salt, pepper, and red pepper flakes if using.
Add the drained penne to the skillet and toss to coat evenly with the sauce. Heat through for a couple of minutes.
Remove from heat, stir in the grated Parmesan cheese until melted and well incorporated.
Serve immediately, garnished with additional Parmesan cheese if desired.