creamy mushroom bisque

Name: creamy mushroom bisque
Ingredients: 2 tablespoons olive oil, divided; 1 large onion, chopped; 24 ounces crimini or button mushrooms, trimmed and quartered; 1 1/2 teaspoons kosher salt; 2 cups vegetable broth; 1 bay leaf; 4 sprigs of fresh thyme; 1 small sprig of rosemary; 1 cup cream; 2 tablespoons sherry (preferably Manzanilla); salt and pepper to taste; a drizzle of cream for garnish (optional); sauteed mushroom slices, for garnish; chopped fresh chives, for garnish