Flamed Lemon Bar Recipe

Prep and mix

Preheat oven to 350°F (175°C). Line an 8x8-inch square baking pan with parchment paper, leaving an overhang to lift the bars after baking. In a medium bowl, whisk together 1.5 cups flour, 0.5 cup granulated sugar, 0.125 tsp fine sea salt, and 1 tablespoon lemon zest until evenly distributed.

Cut in butter

Grate the cold butter or cut into small cubes and use a pastry cutter or fingertips to work 0.5 cup cold salted butter into the dry mix until the texture resembles coarse crumbs with some pea-size pieces remaining. Do not overwork to keep shortbread tender.

Bake crust

Press the mixture evenly into the prepared pan, compacting with the back of a measuring cup to create an even layer. Bake in the preheated oven for 18–20 minutes or until the edges are lightly golden and the center is set. Remove from oven and let cool while you prepare the filling. Keep oven on at 325°F (163°C) for filling bake step.

Whisk eggs and sugar

In a large heatproof bowl, whisk together 1 cup granulated sugar, 4 whole eggs, and 2 egg yolks until smooth and slightly pale. Whisk in 3/4 cup fresh lemon juice and 1 tablespoon lemon zest until combined.

Cook curd (stovetop method)

Set the bowl over a saucepan of gently simmering water (double boiler), making sure the bottom of the bowl does not touch the water. Cook, whisking constantly, until the mixture thickens to a custard consistency and registers about 170–175°F (77–80°C) on an instant-read thermometer, about 8–12 minutes. The curd should coat the back of a spoon.

Finish curd

Remove from heat and immediately whisk in 0.5 cup cold diced unsalted butter, one or two pieces at a time, until fully incorporated and the curd is glossy and smooth. Stir in 0.25 tsp kosher salt. Strain the curd through a fine-mesh sieve into a bowl to remove any bits of cooked egg and zest, pressing with a spatula. Allow the curd to cool for 5 minutes.

Bake with crust

Pour the warm lemon curd over the cooled shortbread crust and spread into an even layer. Lower oven temperature to 325°F (163°C) if you turned it off. Bake the assembled bars for 12–15 minutes, until the curd is set at the edges but still slightly jiggly in the center. Remove from oven and cool on a wire rack for 30–45 minutes, then chill in the refrigerator at least 2 hours (or overnight) to fully set.

Sugar top

When bars are fully chilled and firm, lift them from the pan using the parchment overhang. Transfer to a cutting board and cut into 9 or 12 bars with a sharp knife dipped in hot water and wiped dry between cuts for clean edges. Sprinkle about 2 tablespoons granulated sugar evenly over the top surface of each bar.

Flame safely

If flaming, warm 2 tablespoons limoncello (or a high-proof clear spirit) slightly — do not overheat and keep away from open flame until ready. Using a long lighter and a metal or ceramic serving plate set on a heatproof surface, pour the warmed spirit into a small metal ladle and carefully ignite it away from the bars. Tilt the ladle briefly to transfer a small flame to the sugar-topped bars to caramelize the sugar; alternatively, pour a tablespoon over the bars and ignite for a dramatic flaming effect. Important safety: keep a fire extinguisher or damp towel nearby, keep hair and loose clothing back, and do not attempt flambé if uncomfortable. Let the flame burn out completely (a few seconds) before serving.

Alternative torch method

For a safer, controlled finish, use a culinary blowtorch to caramelize the sugar: hold the torch 2–3 inches from the sugar and move it back and forth until the sugar melts and forms an amber, crackly crust. Allow to cool for 1–2 minutes so the sugar hardens.

Garnish and serve

Garnish each Flamed Lemon Bar with a thin lemon slice and a mint leaf if desired. Serve immediately so the caramelized sugar remains crisp. Store any leftovers refrigerated in an airtight container for up to 3 days.