Lemon Sponge Cake:
- 4 large eggs, separated
- 2/3 cup sugar
- 1 lemon, zested
- 1/2 teaspoon vanilla
- 1/2 cup all-purpose flour
- 1/2 cup cornstarch
- 6 egg yolks
- 1/2 cup sugar
- 1/2 cup fresh lemon juice
- 4 ounces (1 stick) unsalted butter, cut into pieces
- 1/2 cup sugar
- 1/2 cup lemon-flavored vodka
- 1 1/2 cups sugar
- 2 tablespoons light corn syrup
- 1/3 cup cold water
- 3 egg whites
- 1/2 teaspoon cream of tartar
- Pinch salt
- 1 1/2 teaspoons vanilla extract
- 1 tablespoon fresh lemon juice
- 1 tablespoon hot water
In a bowl fitted with an electric mixer, whip the egg yolks, 1/3 cup of the sugar, lemon zest, and vanilla on medium-high speed until thick and almost doubled in volume. (The yolks will form slowly dissolving ribbons when the whip is lifted out.)
In a clean bowl, whip the egg whites on medium speed until frothy. Gradually add the remaining 1/3 cup of sugar, and whip on high speed until stiff peaks form. Fold the egg whites into the egg yolk mixture, being careful not to over mix. Sift half of the flour and cornstarch into the egg mixture, and gently fold to incorporate. Repeat with the remaining flour and cornstarch. Pour the batter into the prepared pan and bake for 20 minutes.
Turn the cake180 degrees F, and bake for an additional 15 to 20 minutes, or until a toothpick comes out clean and the cake starts to pull away from the sides of the pan. Remove from the oven and cool on a wire rack.
Lemon Curd: In the top of a double boiler, or in a stainless steel bowl, whisk together the yolks, sugar, and lemon juice. Place over simmering water and whisk until thickened. Remove from the heat and whisk in the butter until all incorporated.
Cover with plastic wrap, pressing down against the surface to prevent a skin from forming. Refrigerate until cool, about 3 hours or overnight.
Citron Syrup: In a small, heavy saucepan, combine the sugar and vodka. Gently heat, stirring occasionally, until the sugar dissolves.
To assemble the cake: Slice the cake into 3 layers horizontally. Place the top layer of cake in the bottom of the springform pan and brush with 1/3 of the citron syrup. Spread 1 cup of lemon curd on top and smooth evenly. Repeat with the remaining 2 cakes layers, citron syrup and lemon curd. Refrigerate while making the Meringue Icing.
In a small, heavy saucepan, combine the sugar, corn syrup, and cold water. Bring to a boil, stirring until the sugar dissolves. Boil, uncovered, until the syrup reaches the soft ball stage (240 degrees F) on a candy thermometer. Remove from the heat.
Meanwhile, in a large bowl, beat the egg whites, cream of tartar, and salt with an electric mixer until frothy. With the machine running, slowly pour the syrup down the sides of the bowl into the whites (being careful not to pour the syrup into the moving wire whisk). When all the syrup has been added, add the vanilla and continue beating until the mixture has cooled and is fluffy, about 3 minutes. Add the lemon juice and water, and set aside.
Remove the cake from the refrigerator and unwrap. Remove the sides of the pan and spread the icing in a thin layer over the sides and top of the cake. Put the remaining icing in a pastry bag fitted with a star tip and decoratively pipe rosettes on top of the cake.
Refrigerate until ready to serve. Prior to serving, with a blowtorch, brown the meringue lightly.
Propane Gas Torch Warning: Propane gas torches are highly flammable and should be kept away from heat or flame, and should not be exposed to prolonged sunlight. Propane gas torches should only be used in well-ventilated areas. When lighting a propane gas torch, place the torch on a flat, steady surface, facing away from you. Light the match or lighter and then open the gas valve. Light the gas jet, and blow out the match. Always turn off the burner valve to "finger tight" when finished using the torch. Children should never use a propane gas torch without adult supervision.