Heat butter and olive oil in large pot or enameled Dutch oven.
Add shallots and sauté until the shallots are soft.
Add mushrooms and sauté until the mushrooms are soft and have released their juices.
Add dried thyme and salt. Sauté for an additional minute.
Add chicken stock (or vegetable broth if you want to keep this dish vegetarian).
Cover pot and simmer for 20 minutes.
Stir in cream cheese, heavy cream and nutmeg. Bring the soup to a very low simmer, but do not boil.
Using an immersion blender, blend the soup until mostly smooth. Leave a few mushrooms intact for texture.
Add 1 tablespoon of lemon juice. Taste and adjust seasoning as necessary.
Serve this soup with a chunk of crusty bread and enjoy.