POTATO-TOMATO GRATIN

Steps:

• Preheat the oven to 350 degrees F.
• Heat a large saute pan or Dutch oven over high heat for 2 minutes. Swirl in 3 tablespoons olive oil, and then add the onions, 1 teaspoon thyme, 1 teaspoon salt and some pepper. Cook 6 minutes, stirring often, and then turn the heat down to medium. Add the butter, and cook 15 minutes, stirring and scraping with a wooden spoon, until the onions start to caramelize. Turn the heat down to low and continue cooking for about 10 minutes, stirring often, until the onions are a deep golden brown. Remove the pan from the heat and set aside.
• Use a mandoline to slice the potatoes into 1/8-inch-thick rounds. Toss them with the cream, 1 teaspoon thyme, 1 teaspoon salt and some pepper.
• Cut the tomatoes into 1/4-inch-thick slices. Arrange them on a plate and season with 1 teaspoon salt and some pepper.
• Place half the caramelized onions in an even layer in a 9-by-9-inch (or equivalent) gratin or baking dish. Arrange one layer of alternating potatoes and tomatoes on top of the onion layer. Layer a couple of slices of cheese and scatter some olives over the cheese. Drizzle with 2 tablespoons of the cream from the potatoes and 1 tablespoon olive oil. Season with 1 teaspoon salt, a healthy pinch of pepper, 1/2 teaspoon thyme and half the basil.
• Scatter the rest of the caramelized onions over the potatoes and tomatoes. Arrange another layer of potatoes, tomatoes and cheese on top; make this layer pretty, because it will be the top of your gratin. Pour the remaining cream from the potatoes and the remaining 1 tablespoon olive oil over the potatoes and tomatoes. Season with 1/4 teaspoon salt, a pinch of pepper, and the remaining 1/2 teaspoon thyme, olives and basil. Press the vegetables down with your fingers. The cream and oil will come up through the layers and coat the vegetables evenly.
• Cover the baking dish tightly with aluminum foil. Bake until the potatoes are tender when pierced, about 2 hours. Remove the gratin from the oven and uncover it, being careful of the steam.
• Turn the oven up to 450 degrees F and return the gratin, uncovered, to the oven. Cook until the juices have thickened and the top is nice and golden brown (as in "gratineed"), another 25 to 30 minutes.