Creating One-Pan Creamy Penne with Spinach and Italian Sausage is simple when you follow these easy-to-follow steps:

1. Cook the Sausage: In a large skillet, over medium heat, add the olive oil. Add the Italian sausage, breaking it apart with a spatula. Cook for about 5-7 minutes until well browned.
2. Sauté Vegetables: Add the diced onion and cook until it’s translucent, about 3-4 minutes. Stir in the minced garlic and Italian seasoning, cooking for an additional minute until fragrant.
3. Add Pasta and Liquids: Pour in the penne pasta, chicken broth, and heavy cream. Stir to combine all ingredients.
4. Simmer: Bring the mixture to a boil, then reduce the heat to medium-low. Cover the skillet and let it simmer for about 12-15 minutes, stirring occasionally, until the pasta is al dente and most of the liquid is absorbed.
5. Mix in Spinach: Once the pasta is cooked, stir in the chopped spinach and grated Parmesan cheese. Allow the spinach to wilt into the pasta, stirring well.
6. Season: Taste and season with salt, pepper, and red pepper flakes if using. Stir everything until well combined and creamy.
7. Serve: Remove from heat, and let it sit for a few minutes before serving.

These steps ensure that your One-Pan Creamy Penne with Spinach and Italian Sausage turns out delicious every time!