How to Make It
Preheat the oven to 450°. In a large bowl, toss the oyster mushrooms with the 2 tablespoons melted butter and season with salt and pepper. Arrange the mushrooms on a large rimmed baking sheet in a single layer and bake for about 20 minutes, or until they have begun to brown and crisp. Remove any crisp mushrooms to a plate; continue baking the rest for 10 minutes, or until crisp.
Meanwhile, in a large nonreactive saucepan, melt the 3 tablespoons butter over moderate heat. When the foam subsides, add the shallots and reduce the heat to low. Cook, stirring a few times, until softened, about 5 minutes. Increase the heat to moderately high and add the cremini mushrooms. Season with salt and pepper and cook, stirring, until wilted, about 4 minutes. Add the wine and boil until reduced by half, about 3 minutes. Stir in the flour until well blended. Gradually whisk in the Rich Chicken Stock and bring to a simmer. Reduce the heat to low, cover and cook until the mushrooms are very tender, about 15 minutes.
Working in batches, puree the soup in a blender until completely smooth. Reheat the soup. Season with the lemon juice and salt and pepper. Ladle into rimmed soup plates and garnish with the chips and chives.