Green Bean Casserole with Parmesan

Bahan-bahan (6 porsi)

• 1 pound fresh green beans (rinsed, trimmed and halved)
• 2 tablespoons butter (preferably reduced fat)
• 1 medium onion (sliced into thin rings)
• 1/2 cup panko bread crumbs
• 2 tablespoons parmesan cheese (fresh grated)
• 1 teaspoon kosher salt
• 2 tablespoons butter (preferably reduced fat)
• 1 onion (medium, diced)
• 12 ounces mushrooms (chopped into 1/2-inch pieces)
• 1 teaspoon salt
• 1 pinch cracked pepper (to taste)
• 1 tablespoon garlic (minced, or 3 cloves)
• 2 tablespoons all-purpose flour
• 1 cup chicken broth ( or stock)
• 1 cup skim milk (2% or full fat)
• 1/3 cup shredded cheddar cheese (or mozzarella)