I found this recipe in this months All You magazine. This is the recipe that was used, but I made some changes to it. I used low fat cheeses, and low fat milk. It turned out great, and I will use it again.
Preheat oven to 375 , butter a 9x13" baking pan and place on a baking sheet lined with foil.
Combine the three cheeses in a large bowl, sprinkle flour over the cheese and toss to coat. Arrange half of the potatoes, overlapping, on the bottom of the baking dish. Season with salt and pepper. Dot with half the butter. Sprinkle half of the cheese mixture on top. Cover with remaining potatoes and dot with remaining butter. Season with salt and pepper.
Bring milk to a boil over medium-high heat. Pour over potatoes. Cover with foil that has been sprayed with nonstick spray. Bake for 45 minutes or until potatoes are tender. Remove foil and sprinkle with remaining cheese mixture on top and bake uncovered until potatoes are very tender, and top is golden brown. about 30 minutes longer. Let stand 10 minutes before serving.