Step 1. Prep the ingredients: Trim the mushrooms, slice the shallots into wedges, remove the sage leaves, soak the cashews, and dissolve the miso in water.
Step 2. Transfer the mushrooms, shallots, garlic, rosemary, and sage to a large baking dish or two, as needed. Add a generous drizzle of olive oil, salt, and pepper. Rub the ingredients to coat.
Step 3. Roast for about 30 minutes, or until the mushrooms are golden and the garlic is softened, tossing the ingredients every 10 minutes. Remove the rosemary sprig when golden brown.
Step 4. Remove about one-fourth of the mushrooms and slice them for topping the soup. Or sauté additional mushrooms for the topping. Add baked ingredinets to blender.