Perfect Lemon Bars

By Cook's Illustrated Published May 1998

Why This Recipe Works

For our perfect lemon bar recipe, we tackled the crust first. White granulated sugar is often the first option bakers turn to for the sort of crust we were after, but we discovered that confectioners' sugar gave us the tenderest texture. The addition of a little cornstarch also helped move the crust in the melt-in-your-mouth direction. To make the filling lemony enough for our lemon bar recipe, we ended up using the juice from three or four lemons, plus some zest. Arriving at a smooth and pleasant texture involved eggs, a little flour for thickening, and, somewhat unexpectedly, milk, which seemed to balance the flavor with the texture.


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The Crust

1 3/4 cups unbleached all-purpose flour
2/3 cup confectioners' sugar, plus extra to decorate finished bars
1/4 cup cornstarch
3/4 teaspoon table salt
12 tablespoons unsalted butter (1 1/2 sticks), at very cool room temperature, cut into 1-inch pieces, plus extra for greasing pan

Lemon Filling

4 large eggs, beaten lightly
1 1/3 cups granulated sugar
3 tablespoons unbleached all-purpose flour
2 teaspoons grated lemon zest from 2 large lemons
2/3 cup lemon juice from 3 to 4 large lemons, strained
1/3 cup whole milk
1/8 teaspoon table salt

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Makes about two dozen 1 1/2- to 2-inch squares

The lemon filling must be added to a warm crust. The 30-minute chilling and 20-minute baking of the crust should allow plenty of time to prepare the filling. If not, make the filling first and stir to blend just before pouring it into the crust. Any leftover bars can be sealed in plastic wrap and refrigerated for up to two days.

1. For the crust: Adjust oven rack to middle position and heat oven to 350 degrees. Lightly butter a 13-by-9-inch baking dish and line with one sheet parchment or wax paper. Dot paper with butter, then lay second sheet crosswise over it (see illustration 1, below).

2. Pulse flour, confectioners’ sugar, cornstarch, and salt in food processor workbowl fitted with steel blade. Add butter and process to blend, 8 to 10 seconds, then pulse until mixture is pale yellow and resembles coarse meal, about three 1-second bursts. (To do this by hand, mix flour, confectioners’ sugar, cornstarch, and salt in medium bowl. Freeze butter and grate it on large holes of box grater into flour mixture. Toss butter pieces to coat. Rub pieces between your fingers for a minute, until flour turns pale yellow and coarse.) Sprinkle mixture into lined pan and, following illustration 2, press firmly with fingers into even, 1/4-inch layer over entire pan bottom and about 1/2-inch up sides. Refrigerate for 30 minutes, then bake until golden brown, about 20 minutes.

3. For the filling: Meanwhile, whisk eggs, sugar, and flour in medium bowl, then stir in lemon zest, juice, milk, and salt to blend well.

4. To finish the bars: Reduce oven temperature to 325 degrees. Stir filling mixture to reblend; pour into warm crust. Bake until filling feels firm when touched lightly, about 20 minutes. Transfer pan to wire rack; cool to near room temperature, at least 30 minutes. Following illustrations 3 and 4, below, transfer to cutting board, fold paper down, and cut into serving-size bars, wiping knife or pizza cutter clean between cuts, as necessary. Sieve confectioners’ sugar over bars, if desired.


Making the Lemon Bars

1.Lay first sheet of paper lengthwise in pan. Dot the first sheet with butter and lay second sheet crosswise over it.

2. Use fingers to press a crust mixture into a 1/4-inch layer over the bottom and about 1/2 inch up the sides of the pan.

3. After cooling the bars, grasp the edges of the lengthwise paper and lift the bars onto a cutting board.

4. Peel the paper down and off the edges, then cut serving-size bars using a knife or pizza cutter.