Instructions

for the lemon curd

Place 1 tablespoon lemon juice in small bowl; sprinkle gelatin over top. Heat 1/2 cup lemon juice in small saucepan over medium heat until hot but not boiling. Whisk 2 whole eggs and 2 yolks together in medium bowl; whisk in 3/4 cup sugar and pinch salt. Whisking constantly, slowly pour hot lemon juice into egg mixture. Return lemon-egg mixture to saucepan and cook over medium heat, stirring constantly with wooden spoon, until mixture registers 170 degrees and is thick enough to coat spoon, about 3 minutes. Immediately remove pan from heat and stir in butter and gelatin mixture until dissolved. Strain through fine- mesh strainer set over medium bowl; set aside.

for the cake

Using serrated knife, split cake horizontally about 2 inches from bottom. Using paring knife or fork, remove inside of cake bottom, leaving 3/4-inch border along sides and bottom. Pour lemon curd into cake cavity, replace top, and wrap tightly with plastic wrap. Refrigerate for at least 6 hours or up to 24 hours.

for the meringue

In bowl of stand mixer, combine corn syrup, remaining 3/4 cup sugar, remaining 2 egg whites, remaining 2 tablespoons lemon juice, and pinch salt. Place over medium saucepan filled with 1 inch barely simmering water, making sure that water does not touch bottom of bowl. Cook, stirring constantly, until mixture registers 160 degrees, 5 to 10 minutes. Attach bowl to mixer fitted with whisk and add vanilla. Whip on medium-high speed until stiff peaks form, 5 to 10 minutes. Adjust oven rack to middle position and heat oven to 425 degrees. Unwrap cake and place on wire rack set in rimmed baking sheet. Using spatula, spread meringue on cake. Bake until tips of meringue are light golden brown, about 5 minutes. Transfer to cake platter. Serve.