For a few years now, I have preferred using stock (organic veggie or chicken) in scalloped potatoes rather than cream or other dairy (so are they still considered "scalloped"?). And since making that change, I've also realized how many different veggies can be layered in between the potatoes!
Any combination of chard, beet greens or spinach will work well between the potatoes. Pile the greens pretty thick as they will cook down a lot. And be sure to season each layer with salt and pepper.
Cover with stock and bake at 350 degrees F until tender (usually 35-45 min). I usually add cheese on top about halfway through so it gets brown and bubbly but doesn't have time to burn (cheddar or monterey jack work well here).
Allow to cool a bit as the stock will continue to be absorbed. Serve with fresh chives and sour cream.