Potato and Jerusalem Artichoke Gratin with Black Truffle Dressing by Chef Alex Guarnaschelli

Preheat the oven to 350F.

Grease the bottom and the sides of the gratin dish with the butter. Spread the minced garlic on the bottom of the dish with the back of a spoon.

Place the potato and sun choke slices in a large sauce and season them liberally with salt and pepper. Mix to blend. Cover them with 2 cups of the cream, 2 cups of the milk and the nutmeg. Mix to blend. Place the saucepan over low heat and simmer gently for 10 minutes. Take care not to stir the mixture too frequently so as not to break up the potatoes as they cook. Stir in 1/2 cup of the parmesan cheese and 1/2 cup of the gruyre cheese. Taste for seasoning.

Heat a large skillet and add the olive oil. When the oil begins to smoke lightly, add the Brussels sprout slices and season them with salt, pepper and the sugar. Saut them for 1-2 minutes, until they wilt slightly. Drain any excess grease, sprinkle with paprika and set them aside.

Arrange a layer of potato, sun choke cream mixture (about 1/3 of the total amount) on the bottom of the gratin dish. Top with a layer (about 1/3 of the total amount) of the Brussels sprouts and sprinkle with some of the remaining parmesan and gruyre cheese. Repeat the same process two additional times taking care that there is enough cheese for the top. Pour any leftover cream over the gratin and top with any remaining cheese. Note: if the gratin seems a little "dry" put some of (or all) of the remaining cream and milk in a bowl, season with salt and pepper, and pour it over the gratin for extra moisture.

Place the gratin dish in the center of the oven and bake until tender when pierced with the tip of a small knife, 40-45 minutes.

Make the vinaigrette: In a medium size bowl, combine the olive and truffle oils. Whisk to blend. Whisk in the black truffle (if using), Sherry, mustard, lemon juice and lemon zest. Whisk to blend. Season with salt and pepper to taste. Set aside.

After the gratin has cooked for about 40-45 minutes, combine the breadcrumbs and the ground almonds. Top the gratin with the mixture and bake for an additional 10 minutes. Set aside to cool four about 20 minutes before serving.

Serve the gratin in the dish it cooked in and drizzle the top with the vinaigrette. Serve additional vinaigrette on the side. Alternatively, cut individual squares and serve on dinner plates with a drizzle of the vinaigrette around the plate