For the sweet tart dough: In a stand mixer fitted with the paddle attachment, beat the softened butter, powdered sugar, and salt. Add the egg and almond flour. When the mixture is creamy, mix in the flour. Blend until a smooth dough forms. Shape into a ball, wrap in plastic wrap, and refrigerate for at least 2 hours. Lightly flour your work surface and roll out the dough with a rolling pin. Line your tart pan with the dough and chill in the fridge for 1 hour or in the freezer. Preheat your oven to 400°F (200°C). Bake for 15-20 minutes.

For the lemon cream: Zest the lemon and place the zest in a saucepan. Add the lemon juice and 1/4 cup sugar (50 g) to the zest and heat gently. Remove from heat just before it boils. In a mixing bowl, whisk the eggs with the remaining sugar. Pour the hot lemon juice over the egg-sugar mixture while whisking. Return everything to the saucepan and cook over medium heat, stirring constantly, until it thickens and comes to a boil. Remove from heat, add the softened gelatin, then stir in the butter, cut into pieces.

Mix until the cream is smooth. Pour the lemon cream into the pre-baked tart shell and refrigerate for 2 hours.

For the Italian meringue: Bring the water and sugar to a boil. Heat the syrup to 240°F (115°C). Begin beating the egg whites until soft peaks form, then slowly pour in the hot syrup along the side of the mixing bowl. Beat on high speed until the meringue is completely cool. Transfer to a piping bag and decorate your tart. Use a kitchen torch to brown the meringue on top.