Make the tomatoes: Preheat the oven to 250°F. Line a large rimmed baking sheet with parchment paper. Arrange the tomatoes, cut sides up, on the lined baking sheet. Drizzle with the 1/4 cup olive oil, then scatter the thyme sprigs on top and sprinkle with the salt and pepper. Bake until the tomatoes shrink and wilt and most of the liquid pooled on top of the tomatoes evaporates, 4 to 5 hours (speed up this process by roasting at 350°F for 1 hour 30 minutes to 2 hours; tomatoes will be less dense in texture, but work well nonetheless). Cool completely, then gently layer the tomatoes in a bowl. Drizzle the remaining 2 tablespoons oil over the tomatoes and seal in an airtight container; the tomatoes will keep, refrigerated, for 1 week.

Make the tart: Preheat the oven to 400°F. Arrange the puff pastry on a sheet of parchment and roll it out slightly (to about 11 × 12 inches). Pierce all over with a fork. Whisk the egg and mustard in a small bowl and brush on the tart, season with the salt and pepper, and sprinkle with the Parmigiano-Reggiano. Bake until the pastry is puffed and golden, 18 to 20 minutes. Cool completely.

To assemble the tart, layer the tomatoes on top of the pastry, scatter the feta on top, garnish with thyme leaves, and sprinkle with salt and pepper. Use a pizza cutter or sharp knife to cut into squares and serve.

From Shabbat by Adeena Sussman, published by Avery, and imprint of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright © by Adeena Sussman 2023.