Drain 1 can sliced pineapple (I use pineapple chunks)
Boil and slice 6 lg. sweet potatoes

Layer in greased casserole - 3 layers potatoes, 2 layers pineapple. Dot each layer generously with butter. In a saucepan melt 1 tablespoon butter. Stir in 1 tablespoon flour and 1/2 cup pineapple juice. Cook until smooth and clear. Pour over ingredients in casserole. Bake in moderate oven (375 degrees) 20 minutes.