1. Bring a large pot of salted water to a boil. Add penne and cook until al dente. Reserve ½ cup of the pasta water, drain the rest, and set pasta aside.

2. In a large skillet, heat olive oil over medium-high. Add sausage in chunks and sear until browned, about 5–6 minutes. Remove from skillet and set aside.

3. In the same skillet, add ground beef. Season with salt and pepper. Cook until browned and fully cooked through. Drain excess grease if needed.

4. Reduce heat to medium. Add butter to the beef, then stir in garlic. Sauté for 1–2 minutes until fragrant.

5. Pour in the heavy cream slowly, stirring constantly. Simmer for 2–3 minutes. Add Italian seasoning, red pepper flakes, and Parmesan. Stir until smooth and slightly thickened.

6. Fold in chopped spinach and cook until wilted. Turn off the heat and stir in mozzarella until melted.

7. Return sausage to the pan and add drained pasta. Toss everything together to coat. Add reserved pasta water a tablespoon at a time if the sauce is too thick.

8. Serve immediately with extra Parmesan, parsley, or chili flakes on top if desired.