I have been thinking about pies lately and my mind drifts back to 2 that I remember from years gone by. The first was at an Amish restaurant and it was a layer of pumpkin pie on the bottom and custard pie on the top. It had a pastry crust. The second was at a cafeteria in Louisiana and it was sweet potato on the bottom with a layer of pecan pie on the top (not just pecans but the whole gooey, sticky, sweetness of a good pecan pie). I haven't ever seen recipes for these and don't know whether to prebake the bottom layers before adding the top layer. Any hints or other combinations?