Savory Apple Cheddar Galette

Wash your hands and clean the work surface. Rinse the onions, apples, and thyme under running water and dry them; remove any damaged areas. Peel and thinly slice the onions. Pick and measure the thyme leaves. Grate the cheddar and refrigerate it. Cut the 8 tablespoons of pastry butter into small cubes, keeping them cold. Leave the apples whole until assembly.

Mix the 1 1/2 cups flour and 1/2 teaspoon salt in the bowl. Add the cubed butter and rub it into the flour with your fingertips until the mixture looks crumbly, with some flattened, pea-sized pieces of butter remaining. These visible pieces help make the crust flaky.

Add the 4 tablespoons cold water and stir with a fork. Squeeze a handful: it should hold together, although the mixture will still look rough rather than smooth. Press the dough together in the bowl, including the loose crumbs, without kneading. Flatten into a thick disk, wrap, and refrigerate for at least 45 minutes.

Meanwhile, melt the remaining 1 tablespoon butter in the skillet over medium-low heat. Add the onions and their 1/4 teaspoon salt. Cook for 30–35 minutes, stirring frequently, until deeply softened and golden. Lower the heat if the edges brown before the onions soften; the finished onions should be moist but not watery. Stir in 1 teaspoon thyme and 1/4 teaspoon pepper. Spread on a plate and let cool for 10–15 minutes.

Heat the oven to 400°F (200°C), with a rack in the lower third. Set out the baking sheet and a sheet of parchment large enough to hold a 14-inch dough round.

Core the apples and cut them into slices about 1/8 inch thick, leaving the skins on. Toss in the cleaned, dried mixing bowl with the remaining 1/4 teaspoon salt, 1/4 teaspoon pepper, and 1 teaspoon thyme.

Use the reserved 2 tablespoons flour to lightly dust the parchment, dough, and rolling pin. Roll the dough on the parchment into a roughly 14-inch circle, about 1/8 inch thick. An uneven edge is fine. If it cracks, pinch it back together; if it is too firm to roll, let it stand for 5 minutes. Slide the parchment and dough onto the baking sheet.

Scatter all the cheddar over the center, leaving a 2-inch border uncovered. Spread the cooled onions over the cheese, then arrange the apple slices in thin, overlapping layers over the onions. Leave any liquid that has collected in the apple bowl behind.

Lift the uncovered pastry border over the edge of the filling, making loose, overlapping folds as you work around the circle. Press overlapping folds gently so they hold together, leaving the center open. Pinch any tears closed to help contain the cheese. Refrigerate the assembled galette for 15 minutes to firm the butter.

Bake for 45–50 minutes, until the pastry is deeply golden, the apples are tender when pierced with a knife, and the underside is browned and firm when gently lifted with a wide spatula. If the base is still pale, bake for another 5–10 minutes.

Let the galette rest on the baking sheet for 10 minutes before cutting into four wedges. Serve warm. Refrigerate leftovers in a covered container within 2 hours, within 1 hour if the room temperature exceeds 90°F (32°C).