Peel and slice potatoes into thin even rounds.
Arrange slices in overlapping layer on parchment-lined baking sheet.
Sprinkle cheese and pepper, drizzle with oil, and bake at 400°F until tender.
Sauté onion and garlic in a skillet until soft.
Add cubed chicken and herbs; cook until browned.
Stir in mushrooms and cook until softened.
Make cream sauce by melting butter, whisking in flour, then adding milk.
Pour sauce over chicken mixture and combine.
Spread filling on potato sheet, roll into a log, and slice into pinwheels.
Serve warm with a simple salad.