Lemon Squares by America's Best Test Kitchen

America's Best Test Kitchen is one of my trusted kitchen bibles. Just about every recipe I've tried there has worked out well, probably because the recipes have gone through so much testing!

My new favorite is their lemon squares. The lemon part is really custardy, and the crust is super easy to make. The only thing is that it is a bit tricky to build up the crust since it is so dry and crumbly when you blend it in the food processor (I have also tried the alternative method of grating frozen butter into the dry ingredients. Works wonderfully. Genius, really).

Ingredients
The Crust

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

The Filling
4 large eggs — beaten lightly
1 1/3 cups granulated sugar
3 tablespoons all-purpose flour
2 teaspoons finely grated zest — (from two large
lemons)
2/3 cup fresh lemon juice — (from 3 to 4 large
lemons), strained
1/3 cup whole milk
1/8 teaspoon salt


Directions

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.

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. Sprinkle mixture into lined pan and 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. (I had to bake for an additional 10 minutes to make sure the crust is really golden brown. Otherwise it will taste raw).

(If you do not have a food processor, combine the dry ingredients in a big bowl, grate frozen butter over the large hole setting of your grater over the dry ingredients, toss to combine with your fingers)

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

This is pretty good at room temperature and some say even better chilled!