Preheat oven to 375 degrees F.
Spray 8 muffin tins with vegetable spray. Layer potato slices, cheese, and onions into each muffin cup. Season with salt and pepper and top each gratin with 1 or 2 tablespoons of heavy cream. Cover with foil and bake for 30 to 40 minutes, removing the foil halfway through cooking time. Invert gratins onto plate and serve.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.