Bright, tangy, and impossibly elegant, lemon squares (also known as lemon bars) are a beloved American classic. This version elevates the traditional recipe with a gluten-free shortbread base made from a trio of rice flour, oat flour, and almond flour, creating a crumbly, delicate foundation. The topping is a luscious, silky lemon curd that strikes the perfect balance between sweet and tart. Baked in a rectangular pan and cut into neat squares, these treats are best chilled for a few hours before serving. The result is a refreshing dessert that disappears from the table in minutes. Feel free to experiment—swap lemon for lime or add a pinch of spice. For the finest texture, ensure your glass food processor can handle the nut flours without overheating.
About Lemon Squares
Lemon squares originated in the United States as a simple yet sophisticated dessert, often served at picnics and potlucks. This rendition stays true to the original while introducing a gluten-free twist using alternative flours. The shortbread base relies on a mix of rice flour, oat flour, and almond flour, which adds nuttiness and a tender crumb. The curd topping is made from fresh lemon juice, butter, cream, and eggs, cooked gently until thick and glossy. The entire dessert is then baked, cooled, and sliced. For best results, use a non-toxic immersion blender to emulsify the curd if needed. The recipe yields a balanced, refreshing sweetness that pairs beautifully with a cup of tea or coffee.
Ingredients
- 60 g almond flour
- 45 g oat flour
- 15 g starch (corn or potato)
- 85 g unsalted butter, softened
- 50 g granulated sugar
- 2 tsp vanilla sugar
- Pinch of salt
- 340 g granulated sugar (for curd)
- 235 ml fresh lemon juice
- 140 g unsalted butter (for curd)
- 100 ml heavy cream (33% fat)
- 4 large eggs
- 2 egg yolks
- 2 tbsp powdered sugar (for cream)
- 1 tbsp lemon zest
- Pinch of salt (for curd)
- Powdered sugar, lemon slices, pistachios for garnish
For precise measuring, a planetary mixer can help blend the dough evenly. If you prefer a smoother curd, an oil sprayer ensures a light coating for the pan.
Step-by-Step
Step 1: Prepare the Base
Remove the butter for the dough from the refrigerator beforehand to soften. Preheat the oven to 180°C (350°F). Place a rack in the center. Line a square baking pan with parchment paper. In a large bowl, combine almond flour, oat flour, starch, regular sugar, vanilla sugar, and salt. Mix thoroughly. Add the softened butter and quickly knead into a soft dough. Press the dough evenly into the prepared pan, forming a small edge. Bake until golden, about 20–25 minutes. Remove from oven; reduce the oven temperature to 160°C (320°F).
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Step 2: Make the Lemon Curd
For the filling, melt the butter in a small saucepan. Add lemon zest and remove from heat. In a heavy-bottomed saucepan, combine eggs, egg yolks, sugar, and a pinch of salt. Whisk until smooth. While whisking continuously, pour in the lemon juice. Heat over low heat, stirring constantly, for 5–10 minutes until the mixture thickens. Off heat, whisk in the melted butter. Pour the curd over the baked base.
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Step 3: Bake and Chill
Return the pan to the oven and bake at 160°C for 30 minutes, until the curd is set but still slightly jiggly. Cool to room temperature, then refrigerate for at least 8 hours (or overnight). Use a large knife to cut into squares. For clean edges, a refrigerant leak detector isn’t needed here, but a sharp blade is essential.
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Step 4: Garnish and Serve
Whip the heavy cream with powdered sugar into stiff peaks. Dust the lemon squares with powdered sugar and garnish with whipped cream, pistachios, and lemon slices. Serve chilled.
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For a perfect topping, a non-toxic air fryer isn’t used here, but a high-end espresso machine makes a fine pairing.
Tips for Success
- Use fresh lemon juice—bottled juice lacks brightness.
- Chill thoroughly; 8 hours is ideal for clean slices.
- For a nut-free base, replace almond flour with additional oat flour.
- To zest lemons easily, a food processor for nut butter can also grate zest if equipped with a fine grating disc.
- If the curd curdles, strain through a fine mesh sieve and reheat gently.
Variations
Substitute lime juice for lemon to make key lime squares. Add a layer of raspberry jam under the curd for a fruity twist. For a dairy-free version, use coconut cream and vegan butter. To intensify flavor, add a teaspoon of best lava flavors extract? Not exactly—stick to vanilla or lemon extract. For a boozy kick, drizzle with a sweet wine with high alcohol content reduction. Serve with chocolate-covered raisins for an indulgent touch.
FAQ
Can I use regular all-purpose flour instead of gluten-free flours?
Yes, substitute with 120 g of all-purpose flour for the base. The texture will be slightly less crumbly but still delicious.
How long do lemon squares keep?
Store in an airtight container in the refrigerator for up to 5 days. They can also be frozen for up to a month. Thaw in the fridge before serving.
Why is my curd too runny?
Undercooking or insufficient chilling is usually the cause. Ensure you cook the curd until thick enough to coat the back of a spoon, and refrigerate for at least 8 hours. A microwave pressure cooker isn’t recommended for curd, but a double boiler works well.
Can I reduce the sugar?
Yes, cut the sugar in the curd by up to 30% and adjust to taste. The base sugar is minimal and helps structure.
What if I don’t have almond or oat flour?
Grind rolled oats in a wheatgrass juicer? Better to use a clean coffee grinder or food processor. For almond flour, you can grind blanched almonds. Alternatively, use a gluten-free all-purpose blend.
Can I make this ahead for a party?
Absolutely. Prepare up to two days in advance, keep chilled, and garnish just before serving. Pair with George Howell coffee for a refined dessert course.
This lemon squares recipe is a testament to the beauty of simple ingredients and careful technique. The commercial countertop convection oven can handle multiple pans if scaling up. For a stunning presentation, dust with powdered sugar and serve with a dollop of cream. Enjoy the bright, citrusy perfection.
