Chef John's Creamy Mushroom Soup

Ingredients (13)

• + ¼ cup unsalted butter add to pantry
• + 2 pounds sliced fresh mushrooms add to pantry
• + 1 pinch salt add to pantry
• + 1 yellow onion, diced add to pantry
• + 1 ½ tablespoons all-purpose flour add to pantry
• + 6 sprigs fresh thyme add to pantry
• + 2 cloves garlic, peeled add to pantry
• + 4 cups chicken broth add to pantry
• ✓ 1 cup water
• + 1 cup heavy whipping cream add to pantry
• + 1 pinch salt and freshly ground black pepper to taste add to pantry
• ✓ 1 pinch salt and freshly ground black pepper to taste
• + 1 teaspoon fresh thyme leaves for garnish, or to taste add to pantry