Begin by bringing a large pot of salted water to a boil. Add the penne pasta and cook it until al dente, about 7-9 minutes. Drain and set aside.

In a large skillet over medium heat, drizzle in some olive oil. Add the diced onion and sauté until it turns translucent, about 3-4 minutes.

Next, introduce the minced garlic to the skillet. Stir it for about 1 minute until it becomes fragrant.

Crumble the Italian sausage into the skillet. Cook, stirring occasionally, until it’s nicely browned, about 5-6 minutes.

Stir in the canned diced tomatoes and heavy cream. Allow the mixture to simmer gently for about 5 minutes.

Gently fold in the fresh spinach and grated Parmesan cheese until the spinach wilts and everything is well combined.

Finally, add the cooked penne to the skillet. Toss it with the sauce until the pasta is well coated.