Sweet Potato Pie

2 cups mashed, cooked sweet potatoes
2 eggs
1 cup sugar
1 cup milk
1/4 pound butter
1 tablespoon cinnamon
1/4 teaspoon salt
1 tablespoon allspice
1 (9 inch) pie shell, unbaked

Beat potatoes with eggs, sugar and milk. Add butter, cinnamon, salt and allspice. Pour into pie shell. Bake at 375 degrees for 30 minutes.