Bring a large pot of salted water to a boil and cook the pasta according to package directions until al dente.
While pasta cooks, brown the Italian sausage in a large skillet over medium-high heat, breaking it into small crumbles until cooked through. Drain excess fat.
Add minced garlic to the skillet and sauté for 1 minute until fragrant.
Stir in the chicken broth, heavy cream, Italian seasoning, and red pepper flakes. Bring to a gentle simmer.
Reduce heat to low and stir in the grated Parmesan cheese until melted and the sauce thickens slightly.
Add the fresh spinach to the sauce and stir until wilted.
Drain the pasta and toss it into the skillet with the sauce. Season with salt and pepper to taste and serve immediately.