Heat olive oil in a large skillet over medium heat.
Add the Italian turkey sausage to the skillet, breaking it up with a spoon, and cook until browned and cooked through, about 5-7 minutes.
Add the chopped onion to the skillet and cook until softened, about 3 minutes.
Stir in the minced garlic and cook for 30 seconds until fragrant.
Pour in the chicken broth and diced tomatoes with their juices. Stir to combine.
Add the dried Italian seasoning and crushed red pepper flakes. Bring the mixture to a simmer.
Add the cheese tortellini to the skillet. Cover and cook for 5 minutes, stirring occasionally, until the tortellini are tender.
Reduce heat to low and stir in the heavy cream and grated Parmesan cheese until the sauce is creamy and well combined.
Add the fresh baby spinach and cook for 1-2 minutes until wilted.
Season with salt and freshly ground black pepper to taste.
Remove from heat and sprinkle with chopped fresh basil before serving.