Sweet Potato Pie

1 1/2 cups mashed, cooked sweet potatoes
1/2 cup granulated sugar
1/2 teaspoon nutmeg
1 teaspoon cinnamon
1/4 teaspoon cloves
2 eggs, well beaten
1/2 teaspoon vanilla extract
1/2 teaspoon salt
1/4 cup butter
1 cup milk
1 (9-inch) unbaked pie shell

Combine the first eight ingredients. Melt butter in the milk. gradually pour butter-milk mixture into potato mixture, stirring constantly. Beat gently until well blended and smooth. Bake in a pie shell at 450 degrees F for 10 minutes. Reduce heat to 350 degrees F and bake for 45 minutes or until a silver knife comes out clean.