Step 1

Set 1/2 cup mushrooms aside for garnish. Place mushroom trimming in a medium saucepan. Add chicken stock and bring to a boil. Reduce to a sub-simmer and keep warm.

Step 2

Melt 2 tablespoons butter in a medium saucepan over medium heat. Add shallots and garlic and cook, stirring frequently, until very soft but not browned, about 8 minutes. Add mushrooms (except or garnish) to pot and cook, stirring frequently, until excess liquid evaporates and mushrooms start to sizzle, about 10 minutes.

Step 3

Add flour and stir to incorporate. Cook for 30 seconds. Add sherry or white wine and cook, stirring constantly and scraping bottom of pan, until thick and syrupy, about 1 minute. Place a fine mesh strainer over the soup and pour the mushroom-infused broth through it. Discard mushroom scraps. Add bay leaves and thyme sprigs. Bring soup to a simmer and adjust heat to maintain a bare bubble. Let simmer for 30 minutes.

Step 4

Discard bay leaves and thyme and transfer soup to a blender. Close blender and blend, starting on low speed and slowly getting faster. Once blender is at full speed, add four tablespoons butter, 1 tablespoon at a time, until fully incorporated. Continue blending until completely smooth. Rinse out pot and pour soup back into it through a chinois or fine mesh strainser. Season to taste with salt and pepper.

Step 5

To serve, heat oil in a medium saucepan over high heat until lightly smoking. Add reserved mushrooms and cook, tossing continuously, until browned, about 2 minutes. Add minced shallots and thyme sprigs and toss until fragrant, about 15 seconds. Add 2 tablespoons water and the remaining tablespoon of butter. Remove from heat and season with salt and pepper.

Step 6

Ladle soup into warm bowls and top with sautéed mushroom mixture. Serve immediately.