Heat olive oil in a large skillet over medium heat.
Add Italian sausage to the skillet, breaking it up with a spoon, and cook until browned and cooked through, about 6-8 minutes.
Remove cooked sausage from the skillet and set aside, leaving the rendered fat in the pan.
Add minced garlic to the skillet and sauté for 1 minute until fragrant.
Stir in chopped sun-dried tomatoes and cook for 2 minutes.
Pour in heavy cream and chicken broth, stirring to combine.
Add grated Parmesan cheese, dried Italian seasoning, and crushed red pepper flakes. Stir until the cheese melts and the sauce thickens slightly, about 3-4 minutes.
Return the cooked sausage to the skillet and mix well.
Add chopped spinach and cook until wilted, about 2 minutes.
Season with salt and black pepper to taste.
Serve hot, spooning the creamy sausage mixture over pasta, rice, or crusty bread if desired.