Cheesy Leeks — Three Many Cooks

Ingredients

• 4 tablespoons butter, divided
• 3 large leeks, dark green leaves trimmed, light green and white part quartered lengthwise, sliced thin, and thoroughly rinsed and drained
• Salt and ground black pepper
• 1 tablespoon flour
• ½ cup chicken or vegetable broth
• ½ cup milk
• 2 cups grated extra-sharp grated cheese
• ½ cup dry bread crumbs
• ¼ cup grated Parmesan cheese
• ½ teaspoon dried thyme leaves