Cake batter

1. Place the eggs, sugar, vanilla extract, lemon juice, and zest in the bowl of a stand mixer and beat on high speed with the whisk attachment for 5 to 7 minutes until the mixture doubles in volume.
2. Meanwhile, in a medium bowl, mix and sift together the dry ingredients, cake flour, salt, and baking powder and set aside.
3. In another large bowl, whip the heavy cream with an electric mixer on medium speed until stiff.
4. Lower the speed of the mixer and if possible change the whisk for the paddle attachment and add the dry ingredients.
5. Then add the whipped cream and gently fold with a spatula until you have a well-mixed cake batter.
6. Pour the cake batter into 3 cake pans 6 inches / 15 cm in diameter, lined with parchment paper only in the bottom of the pan (if you have only one pan, bake in 3 batches).
7. And bake in a preheated oven at 320°F/ 160°C for about 40 minutes. (check the baking by plunging a toothpick into the center of the cake, it should come out clean which indicates that it is well baked in the center)
8. Let the cakes cool a little before gently running a knife around the edges and unmolding them.
9. Then place them upside down on a wire rack to cool completely.
10. Cover with plastic wrap and place the cakes in the fridge until ready to assemble.

Lemon curd filling

1. Heat the eggs, sugar, lemon juice, and zest in a double boiler, stirring constantly with a whisk until the mixture thickens (about 15-20 minutes).
2. Remove from heat and stir in the butter pieces with a whisk until you have a smooth cream.
3. Strain the mixture through a fine sieve, then cover and place in the fridge until cool.

Mascarpone frosting

1. When assembling the cake, make the mascarpone whipped cream by mixing together all the ingredients in a medium bowl, the cold mascarpone cheese, the cold heavy cream, the powdered sugar, and the vanilla extract.
2. Beat with an electric whisk for about 3 minutes at medium speed until you have a firm whipped cream.

Meringue frosting

1. Place the egg whites in the bowl of a stand mixer fitted with the whisk attachment and mix at slow-medium speed.
2. Meanwhile, prepare the sugar syrup by mixing the sugar and water in a saucepan and heat the pan over medium heat while controlling the temperature, which should be at least 244°F/ 118°C.
3. Turn down the speed of the mixer and gently pour the syrup over the frothy whites, then continue at high speed for about 10 minutes until you have a firm, shiny meringue.

Assembly

1. Place the first layer of cake on a cake board placed on a turntable.
2. First, apply a layer of mascarpone frosting, form a hollow to fill in the center with lemon curd, and cover again with mascarpone frosting.
3. Cover with the second layer of cake and repeat the last step and finish with the third layer.
4. Cover the whole cake with a thin layer of mascarpone frosting with an angled spatula.
5. Decorate the whole cake with Italian meringue and then blowtorch the frosting.
6. Serve immediately or keep the lemon meringue cake chilled until ready to serve.