Reserve about 1/4 cup of the best-looking wild mushrooms. In a large Dutch oven or heavy-bottomed pot, melt 1 tablespoon of butter with the olive oil over medium-high heat. Add the reserved mushrooms and sauté until browned and slightly crisp. Remove and set aside for garnish.

Add the remaining 1 tablespoon of butter to the pot. Reduce heat to medium and add the minced shallots. Sauté until translucent, about 4-5 minutes. Add the minced garlic and fresh thyme, cooking for another minute until fragrant.

Add the remaining sliced mushrooms (Cremini, Shiitake, Oyster) to the pot. Cook, stirring occasionally, until the mushrooms have released their moisture and started to brown significantly, about 10-12 minutes. This step is crucial for developing deep mushroom flavor.

Deglaze the pot by pouring in the dry sherry (or white wine), scraping up any browned bits from the bottom. Let the sherry reduce almost completely, about 2 minutes. Add the broth and Worcestershire sauce (if using). Bring to a simmer, then reduce heat to low, cover partially, and let the soup base cook gently for 20 minutes to allow flavors to meld.

Carefully transfer the soup mixture in batches to a high-powered blender (or use an immersion blender directly in the pot). Blend until completely smooth and velvety. Return the pureed soup to the pot over low heat.

Stir in the heavy cream. Heat gently until warmed through—do not boil once the cream is added. Season generously with kosher salt and freshly ground black pepper to taste. Adjust seasoning as necessary.

Ladle the hot soup into bowls. Garnish each serving with the reserved sautéed mushrooms and a sprinkle of fresh chopped parsley before serving immediately.