1 ½ cups 375mL Carnation® Simple White Sauce, prepared
2 tbsp 30mL butter, divided
1 chopped onion
3 cloves garlic chopped
1 pack 227g sliced mushrooms
1 chopped red pepper
1 bag 750g frozen green beans
3 cups 750mL cooked diced potatoes
4 cups 1L shredded mozzarella cheese, divided
2 cups500mL panko bread crumbs