Goodbye, cakey or chewy lemon squares. These easy lemon pie bars are made with a creamy custard, jam packed with lemon flavor, on a crisp lemon shortbread crust. The perfect combination of sweet-tart and creamy-crispy.
These aren’t your standard flat, thin lemon squares.
With lemon squares, there’s a thin shortbread-ish crust, topped with a thin layer of flour-based lemon filling. The flour (or sometimes cornstarch) helps to set the bars, but it also bakes into an often gummy-ish consistency.
Don’t get me wrong: I love a good lemon dessert. Lemon is quite possibly my favorite dessert flavor, and I will never turn down a lemon square.
But after finding a jar of my homemade lemon curd in the back of the refrigerator and spreading it on pancakes and waffles and everything in sight for a week or two, I wanted something better.
Something richer and smoother and softer, with more lemon flavor and more creaminess. I wanted lemon curd, except thick enough to slice in a bar farm.
Then I realized what I really wanted was the creamy lemon pie, which is one of my Top 5 Favorite Recipes Ever.
I wanted more of that lemon pie, and I wanted it in a hand-held bar form. So that’s exactly what I made — lemon pie bars, instead of classic lemon squares.
Instead of a flour-based filling like most lemon squares, this has a soft custardy filling made from lemon juice and zest, condensed milk, and egg yolk. That’s it.
Because we’re using lemon juice, we’re able to get a delicious soft custard, without adding starch or worrying about over-cooking the eggs. How is this possible? It’s time for my favorite subject… kitchen chemistry!
Lemon juice is acidic, which lowers the pH of the egg and condensed milk mixture. By lowering the pH, we also lower the temperature at which the egg yolks coagulate, or transition from a liquid to a solid state. As a result, the proteins in the egg yolks break apart and reform into a solid structure at a lower temperature, before the eggs cook to the point of scrambling, resulting in a perfectly smooth filling.
The egg yolk helps to ‘set’ the condensed milk and lemon juice as it cooks, resulting in a firm enough texture that you can slice. The lemon pie filling stays soft and silky smooth, but is just stiff enough to give you a nice clean cut when you slice into the bars – without the cakey or gummy texture that can result from adding flour.
Instead of the graham cracker crust from the lemon pie, I went with a shortbread crust with a little lemon zest. As much as I loved the original graham cracker crust, it can be a little crumbly for a handheld food. Plus, we want something that can last for a few days before getting too mushy.
One of the reasons I really like a shortbread crust is because it doesn’t puff up too much as a base layer. By skipping the classic creaming-together-butter-and-sugar step, we’re not adding additional air and lift into the dough.
Instead, everything gets quickly mixed together in the food processor (or cut the butter in by hand), making these super simple.
I also like shortbread crusts because they’re not too sweet — a nice contrast to the rich lemon pie filling.
Unlike the actual lemon pie, lemon pie bars are best topped with a thorough dusting of confectioners sugar. I mean, is it really a lemon bar without that beautiful coating? Just wait until immediately before serving; the sugar will melt into the bars within a half hour or so!
I love the look of perfectly crisp lines outlined with a coating of powdered sugar, but if it’s not your thing, go with a dollop of whipped cream. Or some berries and sprig of mint. Or naked – just let the delicious sweet-tart lemony goodness shine.
Lemon Pie Bars can be stored at room temperature for one day, refrigerated for up to one week or frozen for up to 3 months. Thaw overnight in the refrigerator before enjoying.
A Bunsen Burner Bakery Original Protocol
As an Amazon Associate and member of other affiliate programs, I earn from qualifying purchases.
This Lemon Pie Bar recipe was originally published on 07/30/2018 and was republished with updated text and tips on 07/30/2020.