Mix 300 g wheat flour, 150 g butter, 100 g powdered sugar, and 1 egg in a food processor, and blend until it forms a firm dough. Finish by kneading the dough on the table and refrigerate for 30 minutes.

Roll out the dough on a floured surface. Place the tart dough in a non-stick tart tin and cover it with a piece of baking paper, fill the tart tin with dried chickpeas. Bake the crust for 15 minutes at 170 degrees Celsius (338 degrees Fahrenheit), regular oven. 

Let the tart crust cool on a wire rack with the chickpeas still in.

 

Split half a vanilla pod, and put the vanilla seeds in a bowl along with 100 g of sugar, 1.5 dl heavy cream, 2 eggs, ½ tsp cornstarch, and the zest and juice from 3 lemons. Blend it all together with a hand blender. 

Remove the chickpeas and baking paper, and pour the lemon cream into the tart crust. 

Bake the tart crust and lemon cream for 35-40 minutes at 110 degrees Celsius (230 degrees Fahrenheit) in a regular oven (or until the lemon cream is set).

Let the tart cool for at least 3 hours before removing it from the tin. (For best results, use a tart tin with a removable bottom.)

Whisk 100 g egg whites and 85 g powdered sugar into a stiff meringue, it should form firm peaks.

Put the meringue into a piping bag with the desired nozzle. Pipe the meringue in whichever pattern you prefer.

(If piping bags and nozzles aren't your thing, use a spoon, knife, or any other tool to spread the meringue.)

Lightly torch the meringue with a blowtorch until it's golden on top; this can also be done in the oven. However, I haven't tried this oven method myself.

The tart is ready to serve.