Part 16/26:
To bind the dish together, the chef prepares a creamy sauce made with half-and-half, horseradish, and fresh thyme. The horseradish adds a subtle heat and complexity that balances the natural sweetness of the potatoes.
After pouring the sauce over the layered vegetables, the gratin is topped with shredded Gruyère cheese, which melts and forms a golden-brown crust on top.
The combination of the smoky, roasted vegetables, the rich and tangy sauce, and the melted cheese creates a truly decadent and satisfying side dish. The sweet potatoes take on a savory, almost Thanksgiving-like flavor profile, making this gratin a unique and delicious addition to any holiday table.