Lemon bars are prized for their tangy sweetness, but the bright acidity of lemon juice can read a little one-note. To bring balance to this sunny dessert, the cooks at Christopher Kimball’s Milk Street incorporate a small measure of fruity, savory olive oil in both the custard and crust.
In our book, “ Milk Street Bakes,” we bring balance to the sunny dessert by incorporating a small measure of fruity, savory olive oil in both the custard and crust. If you have a bottle of top-shelf olive oil, this is the time to use it, though high-quality supermarket brands work well, too. Just be sure to use extra-virgin olive oil, which has far more character than refined regular and light olive oils.
Using egg yolks in addition to whole eggs boosts both richness and color. Don’t vigorously whisk the eggs and sugar when making the filling or the mixture will become aerated, which will result in a bubbled surface on the baked bars. Whisk gently and only until the eggs and sugar are combined. For incorporating the flour and liquids into the filling base, we prefer to stir with a silicone spatula to avoid additional aeration.
Buttery pistachios and fragrant lemon zest are mixed into the shortbread base, providing citrusy and nutty notes. With their subtle sweetness and vivid green hue, raw pistachios are worth seeking out. If you can’t find them, the bars still are delicious made with roasted pistachios — just be sure they’re unsalted.
A little heavy cream in the lemon filling tamps down any harsh, brassy notes and lends a smooth, round richness. The bars hold well at room temperature for up to three days. For the cleanest cuts, allow the bars to cool completely before slicing. Dust them with powdered sugar only just before serving, or the sugar will dissolve.
Lemon and Pistachio Bars
Start to finish: 1¾ hours (30 minutes active), plus cooling Makes 24 bars
For the crust:
113 grams (8 tablespoons) cold salted butter, cut into ½-inch cubes, plus softened butter for the pan
145 grams (1 cup) raw pistachios (see headnote)
1 tablespoon grated lemon zest
195 grams (1½ cups) all-purpose flour
161 grams (¾ cup) white sugar
¾ teaspoon table salt
2 tablespoons extra-virgin olive oil
1 large egg white, beaten
For filling and finishing:
5 large eggs, plus 3 large egg yolks
375 grams (1¾ cups) white sugar
1 tablespoon grated lemon zest, plus 1 cup lemon juice
33 grams (¼ cup) all-purpose flour
¼ teaspoon table salt
1/3 cup heavy cream
3 tablespoons extra-virgin olive oil
Powdered sugar, to serve
To make the crust, butter a 9-by-13-inch baking pan or glass baking dish. In a food processor, process the pistachios and lemon zest until finely chopped, about 30 seconds. Add the flour, sugar and salt; process until well combined, 10 to 20 seconds. Scrape the bowl and pulse a few times to ensure no dry, floury patches remain. Scatter the butter over the mixture and drizzle in the oil, then process until large, evenly moistened clumps form, 45 to 60 seconds.
Crumble the dough clumps into the prepared pan, evenly scattering the bits. Using your fingers, press into an even layer. Lightly brush with the beaten egg white and refrigerate, uncovered, until cold and firm, about 30 minutes. Meanwhile, heat the oven to 350°F with a rack in the middle position.
Bake the crust until golden brown, 22 to 26 minutes. While the crust bakes, make the filling. In a large bowl, combine the whole eggs and yolks, sugar and lemon zest; whisk gently just until smooth (avoid aerating the mixture). Add the flour and salt; stir with a silicone spatula until combined. Stir in the lemon juice, cream and oil.
When the crust is done, remove the pan from the oven. Gently stir the filling to recombine, then pour it onto the hot crust; if any large bubbles rise to the surface, pop them with a toothpick or skewer. Return to the oven and bake until the filling is set, 24 to 27 minutes. Cool completely in the pan on a wire rack, about 3 hours.
Using a sharp knife, cut the bars in the pan lengthwise into quarters, then crosswise into sixths, creating 24 squares. Remove from the pan with an offset spatula. Dust with powdered sugar just before serving.