Ingredients Breakdown & Why They Matter
Shortbread Crust
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Shortbread cookie crumbs (2¼ cups): Using cookies for the crust is a shortcut to achieve a perfectly buttery, crumbly base without making dough from scratch. Classic shortbread cookies work best for their buttery, sweet flavor and sturdy texture.
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Unsalted butter (3 Tbsp, melted): Butter binds the crumbs and bakes into a crisp, golden crust. Use good quality butter for maximum flavor.
Lemon Filling
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Granulated sugar (1½ cups):Sweetens the tart lemon juice, balancing the flavor.
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Salt (pinch): Enhances all flavors, cutting through sweetness and brightening lemon notes.
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Fresh lemon juice (½ cup):Provides the key tartness and freshness. Freshly squeezed lemons are a must for bright, authentic flavor.
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Lemon zest (zest of 1 medium lemon): Adds intense citrus aroma and flavor. Don’t skip this!
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Eggs (4 large, room temp):Eggs help the filling set into a smooth custard-like consistency.
Marshmallow-Style Meringue
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Egg whites (4 large, room temp): Whipped into a fluffy foam, they create the classic meringue topping.
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Granulated sugar (¾ cup):Sweetens and stabilizes the meringue, helping it hold stiff peaks.
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Cream of tartar (pinch, optional): Stabilizes egg whites and prevents overbeating or weeping.
Equipment You’ll Need
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9×9 inch square baking pan
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Aluminum foil (for lining)
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Nonstick cooking spray
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Mixing bowls (heatproof for double boiler)
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Whisk and electric mixer (stand or hand)
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Candy or instant-read thermometer (to reach 135°F when heating meringue)
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Kitchen torch or oven broiler
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Sharp knife
Step-By-Step Directions with Tips
1. Preheat & Prep Your Pan
Set your oven to 350 °F (177 °C). Line the 9×9 pan with foil, leaving about 2 inches overhang on two sides for easy lifting later. Spray lightly with nonstick spray—this ensures the bars don’t stick to the foil and come out clean.
2. Make the Shortbread Crust
Combine the shortbread cookie crumbs and melted butter in a bowl. Mix until crumbs are fully coated and resemble wet sand.
Press the mixture firmly into the bottom of the prepared pan to create an even layer. Use the bottom of a measuring cup or glass to press firmly and evenly.
Bake for 14 minutes until the edges just start turning golden. The crust will firm up as it cools but this initial bake keeps it from getting soggy under the filling.
Remove from oven and let cool slightly while preparing the filling.
3. Prepare the Lemon Filling
In a large bowl, whisk together the sugar, salt, and lemon zest.
Add the fresh lemon juice, whisking until combined.
Add eggs one at a time, whisking well after each until the mixture is smooth and homogenous.
4. Bake the Lemon Layer
Pour the lemon filling over the warm crust, smoothing the top with a spatula.
Return the pan to the oven and bake for 18–22 minutes, or until the edges are set but the center still jiggles slightly when shaken. This ensures the filling will set perfectly once chilled.
Remove from oven and place on a wire rack to cool for 30 minutes.
Transfer to the refrigerator and chill for at least 3 hours to fully set the lemon layer before adding meringue.
5. Make the Marshmallow Meringue
Set a heatproof bowl over a pot of simmering water (double boiler setup).
Combine the egg whites, sugar, and cream of tartar in the bowl.
Whisk constantly until the mixture reaches 135 °F (soft-ball stage) or until the sugar has fully dissolved (no graininess when rubbed between fingers).
Remove from heat and transfer the mixture to a stand mixer. Beat on high speed for 3–5 minutes, until the meringue forms stiff, glossy peaks.
6. Top & Brown the Meringue
Using the foil overhang, lift the chilled lemon bars out of the pan and onto a baking sheet lined with parchment.
Spread the meringue evenly over the lemon layer, creating decorative swirls and peaks with the back of a spoon.
Use a kitchen torch to toast the meringue until golden brown, being careful not to burn it.
If you don’t have a torch, place under the oven broiler for 20–30 seconds, watching closely.
7. Slice & Serve
Let the bars rest for 5 minutes after browning.
Dip a sharp knife in hot water and wipe dry between each cut for clean slices.
Cut into 12 equal squares and serve immediately for best texture.