Heat olive oil in a large deep skillet or Dutch oven over medium heat.
Add the Italian turkey sausage, breaking it up with a spatula, and cook until browned and cooked through, about 5-6 minutes.
Add the diced onion and cook until softened, about 3 minutes.
Stir in the minced garlic, dried Italian seasoning, crushed red pepper flakes, salt, and black pepper; cook for 1 minute until fragrant.
Pour in the chicken broth and water, scraping up any browned bits from the bottom of the pan.
Add the uncooked penne pasta and stir to combine.
Bring the mixture to a boil, then reduce heat to medium-low, cover, and simmer for 12-15 minutes, stirring occasionally, until the pasta is tender and most of the liquid is absorbed.
Stir in the chopped spinach and cook for 1-2 minutes until wilted.
Remove the pan from heat and stir in the grated Parmesan cheese, heavy cream, and shredded mozzarella until the cheese is melted and the sauce is creamy.
Sprinkle chopped fresh basil over the pasta and serve immediately.