I like both your's and contessa's recipes... mine was just the basic...
I always add lots of thinly sliced onions... and enough flour to make the juices thick...
usually par-boil the potato slices, pre-soaked also...
I hate crunchy potatoes in this! they have to be cooked "aldente" before adding to casserole...
I slice mine about 1/4" thick...
sometimes I will top with thin cut pork chops, or layer with leftover spiral cut ham...

Cheese is definately Au Gratin, and can be done same way with addition of cheese...
personally, I like it better without the cheese...