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.

The crust:

• 1 cups flour
• 2/3 cup powdered sugar, plus extra for decoration
• cup cornstarch
• tsp. salt
• 12 tbl. unsalted butter at very cool room temp., cut into 1-inch pieces

Lemon filling:

• 4 large eggs, beaten lightly
• 1 1/3 cups granulated sugar
• 3 tbl. flour
• 1 tsp. finely grated lemon zest from 1 large lemon
• 2/3 cup juice from 3 large lemons, strained
• 1/3 cup whole milk
• 1/8 tsp. salt

1. For the crust: Lightly butter a 13-by-9-inch baking pan and line with one sheet of parchment paper. Dot paper with butter and then lay a second sheet crosswise over the first.
2. Pulse flour, powdered sugar, cornstarch, and salt in food processor to blend. 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, -inch layer over entire pan bottom and about inch up sides. Refrigerate for 30 minutes. Meanwhile, adjust oven rack to middle position and preheat oven to 350 degrees. Bake crust until golden brown about 20 minutes.
3. For the filling: While crust is baking, whisk eggs, sugar and flour in a medium bowl then stir in lemon juice, zest, mile 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. Holding edges of parchment paper, lift whole cake out of pan and transfer to cutting board, fold paper down sides and cut into serving-size squares or bars, wiping knife clean between cuts. Sieve more powdered sugar over bars, if desired.