Add the mushrooms and sauté until golden brown, about 5-8 minutes.
Add the shallots and garlic and cook until the shallots are soft, about 3 minutes.
Sprinkle salt and pepper over the mushroom mixture and mix to combine.
Add the broth slowly, deglazing the pan with a wooden spoon as you add the liquid. Bring to a boil.
Stir in the heavy cream. Taste and add any additional salt or pepper to your liking. Allow to simmer on the stove for 10 minutes or until thickened.
While simmering, add the arrowroot to 1 TBS water. Mix to combine. After 10 minutes add the arrow root mixture to the soup and stir. Allow to simmer for an additional 3 minutes.
For a creamier soup, add one cup of the soup to a blender and blend until smooth. Add back to soup pot.
Optional: Top with fresh parsley, fresh, chopped chives or with a swirl of balsamic vinegar for a deeper flavor. For a crunch, serve with parmesan cheese crisps or whole roasted mushrooms.
Notes
Conversions for thickeners: 1 tsp arrowroot = 1 tablespoon flour or 1 1/2 teaspoons cornstarch.