Ombré Citrus Tart

To make the custard, in a saucepan over medium heat, combine the milk, lemon peel, butter, vanilla and salt and cook, stirring occasionally, until the butter is melted and mixture is at a gentle simmer, about 5 minutes. Remove from the heat.

Meanwhile, in a medium bowl, whisk together the egg yolks and sugar until pale and fluffy, about 3 minutes, then whisk in the cornstarch. Remove the lemon peel from the milk mixture and discard. Slowly pour the milk into the egg mixture, whisking constantly until combined. Return the mixture to the pan, place over medium heat and cook, whisking constantly, until the mixture is thick enough to coat the back of a wooden spoon, about 3 minutes.

Strain the mixture through a fine-mesh sieve into another medium bowl. Whisk in the lemon juice until smooth. Press a piece of plastic wrap directly onto the surface of the filling, then refrigerate for at least 2 hours or up to 3 days.

To make the tart dough, in a small bowl, whisk together the egg yolk, water and vanilla; set aside.

To make the dough by hand, in a large bowl, stir together the flour, sugar and salt. Using a pastry cutter or 2 knives, cut in the butter until the texture resembles coarse cornmeal, with butter pieces no larger than small peas. Add the egg yolk mixture and mix with a fork just until the dough pulls together.

To make the dough in a stand mixer, in the mixer bowl, stir together the flour, sugar and salt. Fit the mixer with the flat beater, add the butter and beat on medium-low speed until the texture resembles coarse cornmeal, with butter pieces no larger than small peas. Add the egg yolk mixture and beat just until the dough pulls together.

Transfer the dough to a work surface, pat into a ball and flatten into a disk. Use the dough immediately, or wrap in plastic wrap and refrigerate until chilled, about 30 minutes.

Have ready a rectangular tart pan with a removable bottom that’s about 13 3/4 by 4 1/2 inches (35 by 11.5 cm).

Lightly flour the work surface, then flatten the disk with 6 to 8 gentle taps of the rolling pin. Lift the dough and give it a quarter turn. Lightly dust the top of the dough or the rolling pin with flour as needed, then roll out the dough into a rectangle about 16 by 6 1/2 inches (40 by 16.5 cm), or about 2 inches (5 cm) larger than the dimensions of your tart pan. Carefully transfer the dough to the pan and press it into the bottom and up the sides; trim off any excess dough. Refrigerate for 30 minutes.

Meanwhile, preheat an oven to 350°F (180°C).

Line the chilled tart shell with parchment paper and fill with pie weights. Bake for 20 minutes, then carefully remove the parchment and weights. Continue baking until the crust is golden brown, about 10 minutes more. Transfer the pan to a wire rack and let cool completely, then remove the tart shell from the pan.

To assemble the tart, fill the tart shell with the custard to about a 1/4-inch (6-mm) depth; you may not need all of the custard. Arrange each type of citrus fruit in a separate pile on top of the filling, moving from lightest to darkest, to create an ombré pattern. Cut into slices and serve at room temperature. Serves 8.

Williams Sonoma Test Kitchen