- With the rack in the middle position, preheat the oven to 350°F (180°C). Line the bottom of an 8-inch (20 cm) springform pan with parchment paper. Do not butter.
- In a bowl, combine the flour, baking powder and salt. Set aside.
- In another bowl, beat the eggs, sugar and vanilla with an electric mixer until the mixture turns light and triples in volume, about 10 minutes. Sift the dry ingredients over the egg mixture and fold in with a spatula or a whisk. Spread the batter in the prepared pan.
- Bake for about 25 minutes or until a toothpick inserted in the centre of the cake comes out clean. Let cool on a wire rack. Run a thin blade between the side of the pan and the cake to unmould. Cut the cake into large cubes. You will have 6 to 8 cups of cubes. Set aside.
- In a saucepan off the heat, combine the sugar with the cornstarch and zest. Add the eggs, egg yolks, water and lemon juice and mix thoroughly with a whisk. Cook over medium-high heat, stirring continuously while scraping the bottom and sides of the pan, until the mixture thickens. Remove from the heat.
- Strain the curd through a sieve. Add the butter and stir until smooth. Cover with plastic wrap directly on the surface of the curd. Let cool and refrigerate for about 2 hours or until completely chilled. When ready to use the curd, stir with a spatula to soften it.
- In a saucepan, bring the sugar and water to a boil. Let boil over medium heat until a candy thermometer reads
- In a bowl, beat the egg whites and lemon juice with an electric mixer at medium speed until soft peaks form. When the syrup reaches 240°F (116°C), reduce the mixer speed and slowly drizzle the syrup onto the egg whites while beating. Increase the speed and beat until the meringue has cooled and very stiff peaks form, about 20 minutes. Set aside.
- In a bowl, whip the cream and sugar with an electric mixer until stiff peaks form.
- At the bottom of a 12-cup (3 litre) glass serving bowl, spread ½ cup (125 ml) of the whipped cream. Add half the cake cubes, half the lemon curd, half the cream filling and half the meringue. Repeat the sequence a second time. Refrigerate for 12 hours before serving.
Replacing the sponge cake recipe with a store-bought sponge cake (approximately 200 g) is an easy shortcut.