1 c. fat free half and half
1/2 tsp salt
1/2 tsp pepper
1/4 tsp ground nutmeg
1 large baking potato, peeled and sliced crosswise 1/8" thick
1 large parsnip, peeled and sliced crosswise 1/8" thick
1 large sweet potato, peeled and sliced crosswise 1/8" thick
1 medium celery root, peeled and sliced crosswise 1/8" thick
1/2 c. chopped scallions
1/2 c. grated Parmesan cheese
Preheat oven to 350F. Spray an 8x8 baking pan with cooking spray.
Combine half and half, salt, pepper and nutmeg in a measuring cup. Layer half the baking potato slices in the baking dish, overlapping them slightly. Drizzle with enough half and half to wet them. Layer the parsnip slices over the potato, then top with the sweet potato. Sprinkle the scallions and half the Parmesan cheese evenly on top. Top with the celery root and remaining baking potato. Pour the remaining half and half evenly over the potato and sprinkle with the rest of the Parmesan. Cover with aluminum foil.
Bake on the lowest rack of the oven for 30 min. Remove the foil and continue baking another 30 min., or until bubbly and browned on top. Remove from oven and allow to cool 10 min. before serving.