Root Vegetable Gratin

Name: Root Vegetable Gratin
Ingredients: 1 medium sweet potato (8 ounces), peeled and sliced into ½ inch thick rounds; 1 small or ½ large rutabaga (about 12 ounces), peeled and sliced into 1/8 inch thick rounds; 1½ cups fresh or canned roasted red bell peppers, cut into strips; 3 medium russet potatoes (about 3 pounds), peeled and sliced into 1/8 inch thick rounds; 4 cups shredded sharp cheddar cheese; 6 cups whole or 2 percent milk; 8 tablespoons unsalted butter (1 stick); Pinch ground nutmeg; Salt and freshly ground black pepper; ½ cup all purpose flour