cream of mushroom soup recipe

Ingredients**: - 1 lb fresh mushrooms (button, cremini, or a mix), sliced - 1/4 cup unsalted butter - 1 medium onion, finely chopped - 2 cloves garlic, minced - 1/4 cup all-purpose flour - 4 cups chicken or vegetable broth - 1 cup heavy cream - Salt and pepper to taste - Fresh parsley, chopped (optional, for garnish)