Lemon bars are prized for their tangy-sweetness, but the bright acidity of lemon juice can overwhelm other nuanced flavors and read as a little one-note. 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.