Heat olive oil in a large skillet over medium-high heat.
Add the sliced chicken sausage to the skillet and cook for 5-6 minutes, stirring occasionally, until browned and cooked through. Remove the sausage from the skillet and set aside.
In the same skillet, add the sliced onion and bell peppers. Sauté for 5-6 minutes until the vegetables are softened.
Add the minced garlic, dried Italian seasoning, and crushed red pepper flakes to the skillet. Cook for 1 minute, stirring frequently, until fragrant.
Pour in the chicken broth and use a wooden spoon to scrape any browned bits from the bottom of the skillet. Let it simmer for 2 minutes to reduce slightly.
Reduce the heat to medium-low and stir in the heavy cream and grated Parmesan cheese. Cook for 3-4 minutes, stirring frequently, until the sauce thickens.
Return the cooked chicken sausage to the skillet and stir to coat with the creamy sauce. Cook for an additional 2 minutes to heat through.
Season with salt and freshly ground black pepper to taste.
Remove from heat and garnish with chopped fresh parsley before serving.