This recipe outlines how to create “Classic Lemon Squares,” a beloved dessert featuring a buttery shortbread crust topped with a smooth, tangy, and vibrantly yellow lemon custard. The image displays the dessert in a square pan, both before and after being cut into individual portions, highlighting its distinct layers: a golden-brown, sturdy crust supporting a perfectly set, bright lemon filling. These squares offer a delightful balance of sweet and tart, making them a refreshing treat perfect for picnics, potlucks, or any occasion that calls for a bright, citrusy dessert.
Ingredients:
For the Shortbread Crust:
- 1 cup (2 sticks or 226g) unsalted butter, softened
- ½ cup (60g) powdered sugar (confectioners’ sugar)
- 2 cups (240g) all-purpose flour
- ¼ teaspoon salt
For the Lemon Filling:
- 1 ½ cups (300g) granulated sugar
- ¼ cup (30g) all-purpose flour
- 4 large eggs, at room temperature
- ½ cup (120ml) fresh lemon juice (from about 3-4 lemons)
- 1 tablespoon lemon zest (from about 1-2 lemons)
- Optional: A few drops of yellow food coloring (for a more vibrant yellow, as seen in the image)
For Dusting (Optional):
- 2 tablespoons powdered sugar (confectioners’ sugar)
Equipment:
- 9×13 inch baking pan
- Large mixing bowls (2)
- Electric mixer (stand mixer with paddle attachment or handheld mixer)
- Rubber spatula
- Whisk
- Measuring cups and spoons
- Citrus zester/grater
- Juicer
- Fine-mesh sieve (for dusting powdered sugar)
- Wire cooling rack
Instructions:
Part 1: Prepare the Shortbread Crust
- Preheat Oven: Preheat your oven to 350°F (175°C).
- Prepare Pan: Lightly grease a 9×13 inch baking pan, or line it with parchment paper, leaving an overhang on the longer sides to easily lift the bars out later.
- Cream Butter: In a large mixing bowl, using an electric mixer on medium speed, cream the softened unsalted butter until smooth.
- Add Powdered Sugar: Gradually add ½ cup powdered sugar to the creamed butter, mixing until light and fluffy.
- Add Flour and Salt: Reduce mixer speed to low. Gradually add the all-purpose flour and salt, mixing until the mixture resembles coarse crumbs and just comes together to form a soft dough. Be careful not to overmix.
- Press into Pan: Press the dough evenly into the bottom of the prepared 9×13 inch baking pan. Use the back of a spoon or your fingers to create a firm, even layer, and press it slightly up the sides to form a small crust edge, as visible in the image.
- Pre-bake Crust: Bake the crust for 18-20 minutes, or until lightly golden brown. Remove from oven and set aside while you prepare the filling. Do not turn off the oven.
Part 2: Prepare the Lemon Filling
- Combine Sugar and Flour: In a large mixing bowl, whisk together the 1 ½ cups granulated sugar and ¼ cup all-purpose flour. This helps prevent lumps and ensures a smooth filling.
- Add Wet Ingredients: Whisk in the eggs one at a time until thoroughly combined. Then, whisk in the fresh lemon juice, lemon zest, and optional yellow food coloring until the mixture is smooth and evenly colored.
- Pour over Hot Crust: Carefully pour the lemon filling mixture over the warm, pre-baked shortbread crust in the pan.
Part 3: Bake and Finish the Lemon Squares
- Bake: Return the pan to the oven. Bake for 25-30 minutes, or until the lemon filling is set and the edges are lightly golden. The center should still have a slight jiggle, but it will continue to set as it cools.
- Cool Completely: Remove the pan from the oven and place it on a wire cooling rack. Let the lemon squares cool completely at room temperature. This is crucial for the filling to fully set. Then, refrigerate for at least 1-2 hours, or until thoroughly chilled, to ensure clean slices.
- Slice: Once completely chilled, use the parchment paper overhang to lift the entire slab of lemon squares out of the pan. Place it on a cutting board. Using a sharp knife, cut into squares. Wiping the knife clean between cuts can help achieve clean lines, as seen in the image.
- Dust (Optional): Just before serving, if desired, dust the tops of the lemon squares generously with powdered sugar using a fine-mesh sieve.
Part 4: Serve and Store
- Serve: Serve the Classic Lemon Squares chilled. They are a refreshing dessert on their own.
- Storage: Store leftover lemon squares in an airtight container in the refrigerator for up to 3-4 days. They taste best when chilled.
- Freezing: Lemon squares can be frozen for up to 2-3 months. Place them in a single layer on a baking sheet to freeze, then transfer to an airtight freezer-safe container or bag. Thaw in the refrigerator before serving.
Tips for Success:
- Fresh Lemon Juice and Zest: Always use fresh lemon juice and zest for the best, brightest lemon flavor. Bottled juice will not yield the same vibrant taste.
- Don’t Overbake the Crust: Overbaking the crust can make it too hard. It should be lightly golden and just set.
- Cooling is Crucial: The lemon filling needs ample time to cool and set completely. Rushing this step will result in a messy, runny filling. Refrigeration is essential for clean cuts.
- Sifting Powdered Sugar: Sifting powdered sugar for the crust and for dusting ensures a smooth texture and prevents lumps.
- Variations:
- Lime Squares: Substitute lime juice and zest for lemon for a zesty lime version.
- Coconut Crust: For a tropical twist, add ½ cup of shredded coconut to the shortbread crust mixture.
- Berries: While not traditional, a thin layer of fresh raspberries or blueberries could be scattered over the pre-baked crust before pouring the lemon filling for added fruitiness, similar to a Cranberry Christmas Cake or White Chocolate Raspberry Cheesecake Cookies.
- Baking Pan: A metal baking pan is generally preferred for even heat distribution, though a glass pan works; adjust baking time if using glass as it heats differently.
- Similar Dessert Categories: Lemon squares fall into the category of bar cookies or sheet desserts, which are typically easy to make and serve a crowd. They share a similar base-and-topping structure with other fruit bars or crumb cakes. The use of lemon as a primary flavor is also seen in other desserts like lemon cranberry cake.