1. Sauté the onions and garlic in oil until slightly tender. Remove the pan from the stove.
2. Add the freshly sliced mushrooms to the onion and garlic mixture. Set the pan aside.
3. Grab a large soup pan and melt the butter in it.
4. Add the flour to the soup pot to make a roux, and whisk constantly.
5. Stir in the chicken broth and heavy cream. Continue to stir or whisk constantly.
6. Add the crumbled chicken or beef bouillon cubes. Stir until thoroughly mixed into the soup.
7. Add the onion, garlic, and mushrooms to the soup.
8. Add the Marsala wine and the thyme in the soup pot.
9. Add salt and ground black pepper to taste. Garnish with fresh parsley, if desired.