Lemon bars are simply the best summer dessert. I make several versions but keep coming back to this buttery, creamy lemon squares recipe. The filling is slightly softer than other lemon bar recipes and is a bit more like the filling for a key lime pie. One of my baking tricks is to use duck eggs. If you can find them at your local farmers market, they are the best eggs for baking! You can also double this recipe and use a 13 x 9 baking pan to feed a crowd.
1/2 cup confectioners' sugar, plus more for dusting
1 cup all-purpose flour
1/2 cup butter, chilled, cut into slices
4 large egg yolks (use duck egg yolks, if possible)
1 can (14 ounces) sweetened condensed milk
3/4 cup fresh lemon juice
Preheat oven to 350°. Lightly coat the bottom and sides of an 8 x 8-inch baking pan with non-stick baking spray. Line with a piece of parchment paper, leaving an overhang on two of the sides. Lightly spray the parchment paper, too. (I like to secure the ends of the parchment paper to the sides of the baking pan with a couple of binder clips.)
To make the crust:
Place confectioners' sugar and flour in the bowl of a food processor. Process to combine with a few short bursts. Add the chilled butter pieces and process until the mixture looks like crumbs. Don't over-process. Tip the crumbs into the prepared pan and using your fingers, scatter the crumbs evenly over the bottom. Using a glass or the bottom of a measuring cup, gently press down on crumbs to create a level firm crust. Place in oven and bake until lightly golden, about 15 to 20 minutes.
To make the filling:
In a large mixing bowl, whisk yolks. Add condensed milk and lemon juice and whisk until smooth. Pour mixture over hot crust in pan and return to oven. Bake for 25 to 30 minutes until filling is set.
Allow bars to cool completely in pan, then refrigerate at least 3 hours until filling is chilled. Using the parchment paper overhang, gentle lift the dessert onto a cutting board. Cut into squares and dust with confectioners' sugar.
VARIATION: Substitute freshly squeezed lime juice for the lemon juice. I like using Persian limes but feel free to use Key limes if you can find them.