The filling for these delicious sweet-tart squares is a homemade lemon curd, a thick, smooth lemon-butter sauce that’s often spread on muffins, cakes or even bread. Meyer lemons, beloved for their sweet flavor and flowery fragrance, are used here, but you may substitute common lemons like Eureka. Although the lemon filling remains soft even when cold, it holds its shape once the squares are cut.
Meyer Lemon Squares
Cookie of the Day
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For the crust:
3/4 cup (4 oz./125 g.) all-purpose flour
1/4 cup (1 oz./30 g.) confectioners’ sugar
1/8 tsp. salt
6 Tbs. (3 oz./90 g.) cold unsalted butter, cut into 3/4-inch (2-cm.) pieces
For the filling: 3 large whole eggs, plus 3 large egg yolks
3/4 cup (6 fl. oz./180 ml.) fresh Meyer lemon juice, strained (about 5 lemons)
1 cup (8 oz./250 g.) granulated sugar
6 Tbs. (3 oz./90 g.) unsalted butter, cut into 3/4-inch (2-cm.) cubes
1 tsp. grated Meyer lemon zest
Confectioners’ sugar, for dusting (optional)
Position a rack in the middle of the oven, and preheat to 350 degrees F (180 degrees C). Butter an 8-inch (20-cm.) square baking pan.
By hand: To make the crust, in a large bowl, stir together the flour, confectioners’ sugar and salt until blended. Using a pastry blender or 2 knives, cut in the butter until the mixture forms large, coarse crumbs the size of small peas.
By food processor: To make the crust, combine the flour, confectioners’ sugar and salt and pulse 2 or 3 times until blended. Add the butter and pulse 6-8 times until the mixture forms large, coarse crumbs the size of small peas.
Press the crumb mixture into the bottom and 1 inch (2.5 cm.) up the sides of the prepared pan. Bake the crust until it is golden and the top feels firm when lightly touched, 15-20 minutes. Set aside. Reduce the heat to 325 degrees F (165 degrees C).
To make the lemon filling, in the top of a double boiler, whisk together the whole eggs, egg yolks, lemon juice and granulated sugar until the sugar dissolves. Place over (not touching) barely simmering water and add the butter pieces. Using a large spoon, stir constantly until the butter melts and the mixture is thick enough to coat the back of the spoon and registers 160 degrees F (71 degrees C). on an instant-read thermometer, about 12 minutes. Remove from over the water and strain the lemon curd through a medium-mesh sieve placed over a bowl. Stir in the lemon zest. Let cool for 10 minutes. Pour the lemon curd into the baked crust.
Bake until the center is just set, 13-17 minutes. Transfer to a wire rack and let cool for 20 minutes, then cover and refrigerate until well chilled, at least 3 hours or up to overnight. The filling will thicken further as it cools.
If desired, just before serving, using a fine-mesh sieve, sift a thick layer of confectioners’ sugar over the top of the squares. Using a large, sharp knife, cut into 16 squares and serve. Store in a covered container in the refrigerator for up to 3 days. The confectioners’ sugar tends to melt if stored, however, to it is best not to use it if you will not be serving the squares the same day. Makes 16 squares.