In a large skillet, heat 1 tablespoon of olive oil over medium heat. Add 1 pound of crumbled Italian sausage to the skillet, cooking for about 5 minutes, stirring occasionally until it's golden brown and no longer pink. Once done, drain any excess grease.

Next, stir in 3 cups of uncooked rigatoni pasta, 2 cups of chicken broth, 1 cup of heavy cream, 4 cloves of minced garlic, 1 tablespoon of Italian seasoning, and 1 cup of tomato sauce into the skillet. Mix everything thoroughly.

Increase the heat to medium-high and bring the mixture to a gentle boil. Once boiling, reduce the heat to low, cover the skillet, and let it simmer for 10-15 minutes, stirring occasionally.

Once the pasta is cooked, gently fold in 2 cups of fresh spinach. Stir until the spinach is wilted, which should take about 2 minutes.

If the sauce is too thin for your liking, cook the dish uncovered for an additional 2-3 minutes over low heat, stirring frequently.

Finally, remove the skillet from heat and season your dish to taste with salt, black pepper, and red pepper flakes. Serve immediately, garnishing with freshly grated Parmesan cheese if desired.