1. In a large pot sprayed with nonstick cooking spray, add chicken sausage, diced onions, and mushrooms. Sauté on medium for 5-10 minutes. Add grated garlic, stirring for 1 minute. Add oregano, tomato paste, diced tomatoes, chicken stock, and kosher salt.
2. Simmer for 20 minutes, stirring occasionally. Keep on low until ready to eat, and stir every once in a while.
3. In a small bowl, mix the topping ingredients: ricotta, parsley, grated garlic, and parmesan cheese, and salt. The mixture will turn a pretty green. You can use less parsley if you'd like.
4. When serving, scoop soup into bowls and add a dollop of ricotta-herb mixture. Add in more herbs if desired.