Procedure:

Meringue: Preheat the oven to 140°C/fan120°C/gas 1. In a large, grease-free mixing bowl, whisk the egg whites to soft peaks. While continuously whisking, slowly add the caster sugar – 1 tbsp at a time – until you have a stiff, glossy meringue mixture. Using a pocket bag, place the heart-shaped meringue on the baking paper.
Bake for 1¼ hours for mallowy centres, or 1½ hours if you prefer crisper meringues. Peel off the baking paper, then transfer the mallowy meringues to a wire rack to cool, or leave the crisp ones in the turned-off oven for at least 4 hours to cool slowly, then transfer to a wire rack.

Lemon Cream: Heat the lemon juice.
In a bowl, whisk the 4 yolks plus the 2 whole eggs and the sugar. Mix well and add the maizena. Finally, pour in the hot lemon juice. Cook like a pastry cream and let cool.

Cake assembly: Put the lemon cream in a pastry bag.
Take the Breton shortbread in the shape of a heart and put the lemon cream on top. Finally add the meringue. Your Valentine's Day cake is ready