Heat olive oil in a Dutch oven medium-high heat. Add sausage and cook 3-5 minutes (until browned), crumbling as it cooks; drain excess fat. Add garlic and onion. Cook, stirring occasionally, 3-4 minute (until tender).
Add chicken stock, tomatoes, basil, oregano, red pepper flakes and 1 cup of water. Season with salt and pepper.
Bring to a boil and stir in tortellini. Reduce heat and simmer until tortellini is cooked through (5-6 minutes).
Stir in heavy cream and Parmesan until well combined, about 2-3 minutes.
Serve immediately, garnished with croutons, if desired.