Susan's Perfect Lemon Bars

This recipe is from a Cook's Illustrated article by Susan Logozzo about perfecting the lemon bar. NOTE: The lemon filling must be added to a warm crust. The 30 minute chilling time 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 onto the crust. Prep time includes 30 minute chilling time for crust.

• Ready In: 1 hr 30 mins
• Yields: 12 bars

Ingredients

• Crust

• 1 3⁄4 cups all-purpose flour
• 2⁄3 cup confectioners' sugar (plus extra to sprinkle over finished bars)
• 1⁄4 cup cornstarch
• 3⁄4 teaspoon salt
• 12  tablespoons sweet unsalted butter, at cool room temperature, cut into 1 inch pieces
•  extra butter, for greasing pan

• Lemon Filling

• 4  large eggs, lightly beaten
• 1 1⁄3 cups granulated sugar
• 3  tablespoons all-purpose flour
• 2  teaspoons  finely grated lemons, zest of (from 2 large lemons)
• 2⁄3 cup fresh lemon juice, strained (from 3-4 large lemons)
• 1⁄3 cup  whole milk
• 1⁄8 teaspoon salt

Directions

1. Adjust oven rack to middle position and heat oven to 350°F.
2. Lightly butter a 9 x 13 inch baking dish and line it with a sheet of parchment paper.
3. Dot parchment paper with butter, then lay a second sheet of parchment crosswise over the first one, allowing the ends to extend over the top edge of the pan by about 1 inch.
4. To Mix Crust in Food Processor: In a food processor, fitted with steel blade, pulse together the flour, confectioner's sugar, cornstarch and salt to mix well.
5. Add 12 Tablespoons butter and process to blend (about 8 to 10 seconds), then pulse until mixture is a pale yellow color and resembles a coarse meal, (about three-1-second bursts).
6. To Mix Crust By Hand: Mix flour, confectioner's sugar, cornstarch and salt together in a medium bowl.
7. Freeze butter and grate it on the large holes of a box grater into the flour mixture.
8. Toss butter pieces to coat.
9. Rub coated butter pieces between your fingers for a minute, until flour turns pale yellow and coarse.
10. Sprinkle crust mixture into parchment lined pan.
11. Using both hands, firmly press mixture into an even, 1/4" layer over the entire pan bottom and about 1/2" up the sides.
12. Refrigerate for about 30 minutes.
13. Remove chilled crust and bake at 350°F for about 20 minutes, or until golden brown.
14. Filling: Prepare filling while crust is baking.
15. In a medium bowl, whisk eggs, sugar and flour.
16. Stir in lemon zest, juice, milk and salt; stirring to blend well.
17. Remove crust from oven, and reduce oven temperature to 325°F.
18. Stir filling mixture to reblend and pour over warm crust.
19. Return bars to oven and bake about 20 minutes, or until filling feels firm when lightly touched.
20. Remove from oven and place pan on wire rack to cool until almost room temperature (at least 30 minutes).
21. Grasp the edges of the lengthwise parchment paper (long sides of the pan) and lift the lemon bars out of the pan and onto a cutting board or counter.
22. Carefully peel the paper down from the sides and using a pizza cutter or knife, slice them into serving size bars, wiping pizza cutter or knife clean between cuts as necessary.
23. Sieve confectioner's sugar over bars, if desired.
24. Leftover bars can be sealed in plastic wrap and refrigerated for up to 2 days.