I jokingly consider myself an expert on lemon bars because I ate them every single workday for a year during my first job as a baker. I started each morning by cutting up a tray of lemon bars. My boss insisted that I throw away any bar that wasn’t deemed perfect. I usually just ate them instead. After a year of eating overcooked, undercooked, too tart, too creamy, too sweet, not-just-right lemon bars, I learned the nuances of them all.
Now I have my own bakery, and we can’t seem to make lemon bars fast enough. We make a tart lemon curd filling that has a little cream and butter mixed in to temper the sharpness of the lemon. We pour the curd over a layer of rich, crumbly shortbread, and then we bake until just set. When cool, the bars are cut into pieces and served. The contrast of tart filling and buttery shortbread appeals to everyone.
I must confess, though, that this recipe didn’t start out as a lemon bar. It was originally a lemon tart—a very delicious tart that my customers wouldn’t buy. I decided to change the presentation to squares (perhaps the tart looked too formal?), and I ended up with a best seller. They’re not your classic, thin lemon bars with a dusting of confectioners’ sugar, but that doesn’t seem to matter. These lemon bars fly out the door.
Start with a rich, buttery shortbread
That same perfectionist boss developed a foolproof recipe for shortbread that I now use as the base for my lemon bars. Great shortbread should be tender and rich and have a wonderful, melt-in-your-mouth quality. I cream room-temperature butter with two kinds of sugar: granulated, which aerates the butter and makes a lighter shortbread; and confectioners’, which dissolves quickly and makes a more tender pastry. Then I add a combination of all-purpose flour and cake flour; the all-purpose provides strength, while the softer cake flour ensures tenderness.
A trick we use in the bakery is to line the baking pan with parchment, letting an inch or two extend past the sides of the pan. This makes it easy to remove the bars from the pan once they’ve cooled to room temperature. If you don’t have parchment, just grease your pan with butter. It will be a little trickier to remove the bars, and you may have to sacrifice a bar or two in order to wedge in a spatula.
Pour on a tart lemon curd
Classic lemon bars usually call for a mixture of lemon juice, eggs, and sugar to be poured onto the baked shortbread and then baked again so the topping thickens. Instead, I use lemon curd as my topping because I like its thick, smooth, custardy texture. This recipe makes an intensely lemony, refreshingly tart curd that marries well with the buttery shortbread base. The ingredients are the same, but the curd is fully cooked on the stovetop to thicken it. Only then is it poured over the shortbread and baked.
Bake until they wiggle like jello
These bars are a breeze to put together. You simply pour the curd on the baked shortbread and bake again until the curd is just set. The way to check if the bars are finished baking is with the “ wiggle test.” When you jiggle the pan, the curd should wiggle like firm jello—anything looser and your lemon bars will fall apart once you cut them; if they don’t wiggle at all, then the bars might be overcooked and grainy.
Let the baked bars cool to room temperature and then transfer them to a board and refrigerate. If you refrigerate them while they’re still warm, the topping may crack. Give the bars at least four hours to firm up in the fridge and then cut them into squares.