Melt butter in a large stockpot. Add garlic and mushrooms, and cook, stirring occasionally, until tender and browned, about 5-6 minutes; season with salt and pepper, to taste. Stir in onion and cook, stirring frequently, until translucent, about 2-3 minutes. Stir in wine and bring to a boil; reduce heat and simmer until slightly reduced, about 5 minutes. Stir in chicken broth, heavy cream, 2 egg yolks and thyme. Stir in mixture to the soup until slightly thickened. If the soup is too thin, a...