Make the shortbread dough

1. In a large bowl, beat the softened butter with the powdered sugar, vanilla, and salt until smooth and creamy.
2. Add the flour and mix until a soft dough forms.
3. Shape into a disc, wrap in plastic, and chill for 30 minutes - 1 hour.

Shape the cookies

1. Roll the dough into balls of about 25 g each and place them spaced apart on a baking sheet lined with parchment paper.
2. Flatten slightly with your palm and press an indent in the center using your thumb or the back of a teaspoon.

Chill and bake

1. Place the tray in the fridge or freezer for at least 1 hour.
2. Meanwhile, preheat the oven to 350°F (180°C).
3. Bake for 10–12 minutes, until the edges are just turning golden.
4. Reshape the cookies with a round cutter and redefine the center if needed.
5. Let cool completely.

Make the lemon curd

1. In a saucepan, whisk together the eggs, sugar, lemon juice, zest, and cornstarch.
2. Cook over low heat, whisking constantly, until thickened.
3. Remove from heat and stir in the butter until smooth. Let cool completely.

Make the Swiss meringue

1. Place the egg whites and sugar in a heatproof bowl over a saucepan of simmering water.
2. Whisk constantly until the sugar dissolves and the mixture is warm to the touch.
3. Remove from heat and beat with an electric mixer until stiff, glossy peaks form.

Assemble the cookies

1. Fill each cookie with a spoonful of cooled lemon curd.
2. Pipe a swirl of meringue on top using a decorative tip (like a Saint-Honoré).
3. Lightly toast the meringue with a kitchen torch just before serving.