1. Peel and slice the root vegetables thinly using a mandoline or sharp knife for uniform thickness, ensuring even cooking.
2. Optionally, briefly simmer or boil the sliced vegetables to soften them, which helps achieve the perfect texture and speeds up baking.
3. Prepare the cream mixture by simmering heavy cream, whole milk, or half and half, with added butter or olive oil, garlic, and flour to thicken the sauce. Stir in cheeses such as Gruyère, Parmesan, or preferred options for a rich, creamy base.
4. Start layering the thinly sliced vegetables in a baking dish in a decorative pattern. Ensure even distribution of the slices across the dish.
5. Pour the prepared cream mixture evenly over the layered vegetables, ensuring they are well-coated.
6. Sprinkle a generous layer of grated cheese, such as Parmesan or Gruyère, on top to create a golden, crispy crust during baking.
7. Preheat the oven to 400°F (200°C). Cover the baking dish with foil and bake for about 30 minutes, or until the vegetables are tender.
8. Remove the foil and continue baking for another 18-20 minutes, or until the cheese is melted and lightly browned.
9. Let the gratin cool briefly before serving warm to fully enjoy its creamy, cheesy goodness.
10. Store leftovers properly by refrigerating in an airtight container for up to three days or freeze for longer storage, reheating in the oven or microwave as needed.