Bring a large pot of salted water to a boil. This helps to flavor the pasta as it cooks.

Add the penne pasta and cook according to package instructions until al dente, usually about 10-12 minutes.

Once cooked, reserve 1 cup of pasta water, then drain the pasta in a colander and set aside.

In a large skillet, heat 1 tablespoon of olive oil over medium heat.

Add the Italian sausage, breaking it apart with a wooden spoon. Cook until browned and cooked through, about 5-7 minutes.

Add the chopped onion, garlic, bell pepper, and mushrooms to the skillet. Sauté until the vegetables are softened, about 5 minutes.

Stir in the crushed tomatoes, tomato paste, oregano, basil, red pepper flakes, and chicken broth.

Bring the mixture to a simmer, then reduce the heat to low. Let it cook for about 10 minutes to allow the flavors to meld.

Season with salt and black pepper to taste.

Add the cooked pasta to the skillet with the sauce. Toss to combine, adding reserved pasta water a little at a time if the sauce is too thick.

Cook for an additional 2-3 minutes, allowing the pasta to absorb some of the sauce.

Divide the sausage pasta among plates or bowls.

Top with grated Parmesan cheese and chopped parsley for garnish.

Serve hot and enjoy your delicious sausage pasta!