Step 1

Position racks in the top and bottom thirds of the oven and preheat to 425 degrees.

Step 2

In a large bowl, toss the mushrooms and shallots with 3 tablespoons of the oil and 1/2 teaspoon of the salt. Spread the mushrooms across 2 large, rimmed baking sheets and roast for 10 minutes. Stir, switch the top to bottom and vice versa, rotating each baking sheet front to back, and continue roasting an additional 10 to 15 minutes, or until the mushrooms release their water and brown, and the shallots soften. Remove from the oven and set aside. In a large pot over medium heat, heat the remaining 2 tablespoons of oil until shimmering. Add the garlic and thyme and cook, stirring, until aromatic, 30 seconds. Reserve 1/4 cup of the mushrooms for garnish. Add the remaining mushrooms and the shallots to the pot, along with the broth, beans, pepper and the remaining 1/4 teaspoon of salt. Increase the heat to high and bring to a boil. Reduce the heat to medium-low and simmer, uncovered, for 10 minutes. Stir in the sherry and cook until the flavors meld, 3 minutes more.

Step 3

Using an immersion blender, puree the soup in the pot until smooth. (Alternatively, let cool until not scalding and puree in batches in a regular blender.) Stir in additional broth or water if needed to thin to get your desired consistency. Rewarm the soup if needed, taste, and season with additional salt, if desired.

Step 4

Ladle the soup into bowls, garnish with the reserved mushrooms, a pinch of black pepper, if you like, and parsley, and serve.