Reduce heat to low and add room temperature heavy cream; combine well; cover and cook for 15 minutes
1½ cups heavy cream
Taste for salt and pepper; adjust seasonings to taste; remove thyme sprigs
salt and pepper to taste
If you want a thicker soup, add slurry now; bring soup to boil; stir in slurry and allow soup to cook another 5 minutes or until it reaches desired thickness; (If you want it even thicker, add another slurry to the mixture)
¾ cup water, 2 tablespoons cornstarch
Once soup has reached desired consistency, plate and garnish with thyme
Notes
Do not add cold cream to the hot soup; take the cream out of the fridge and let it sit about 10 minutes before adding it
This recipe uses button (white) mushrooms, but you can substitute with any other cultivated mushroom.
Sometimes, I leave a portion of the mushrooms sliced, just to give added texture. It's up to you. If you want a chunky cream of mushroom soup, don't put the mushrooms in the food processor; just add them (sliced) to the onion and resume recipe.
Want a thicker soup? Add a slurry
This recipe is a relatively thin soup; if you prefer a thicker soup, make a thickening slurry: combine 2 tablespoons of flour or cornstarch with 3/4 cup tap water.
If you use flour in the slurry, keep the heat on low because flour thickens at a lower heat.
If you use cornstarch in the slurry, turn the heat up and bring soup to boil; add in slurry, whisking constantly. Cornstarch thickens at high heat. Allow mushroom soup to cook on high heat until it reaches the desired consistency.
If it's still not thick enough for you, you can either add another slurry or, ladle out about 1/2 cup of soup into a measuring cup, mix in 2 tablespoons of cornstarch, then pour it in the soup
If you add a second slurry, you may have to add a little more sugar and sherry
Adjust salt and pepper after adding slurry
Want a silky smooth soup?
Use an immersion blender or pour soup into food processor and pulse
Do either of these before the soup gets too hot or after it's cooled
A note about this soupAnytime you combine fat (oil) with liquid (broth), you might see a slight oil film on top of the soup, because fat rises to the top. If this bothers you, you can remove the fat by one of these ways:
Let the soup cool in the refrigerator and skim the fat off the top
Use a clean paper towel and gently drag it over the top of the soup