Directions:
1. Melt butter over medium heat in soup pot.
2. Add carrots, onions, leeks, and celery. Cook until tender.
3. Stir in thyme and mushrooms. Cook until mushrooms have softened.
4. Add stock, season with salt and pepper.
5. Simmer covered for 20 minutes.
6. Pull soup off heat and let cool slightly.
7. Puree in a blender, adjust seasonings, and serve.