Sable Breton

Preheat the oven to 350 degrees F (177 degrees C). Prepare your tart pan by lightly greasing it or lining with parchment paper.

In the bowl or a stand mixer with a paddle attachment, mix together the butter, granulated sugar, flour, kosher salt, and vanilla extract until it creates a homogenous, yet very crumbly dough.

Using slightly dampened hands, press the dough crumbs into the prepared dish in an even layer. Use a fork to dock the dough all over so it doesn't puff up while baking.

Bake the tart crust for 30-33 minutes until the crust is completely cooked through. Let cool completely before filling with lemon curd.

Lemon Curd Filling

In a medium saucepan over medium-low heat, whisk together the cornstarch and sugar. Then whisk in everything except the vanilla and butter and whisk constantly until thickened, for 7-10 mins. Keep whisking until the warm lemon curd is nappé, or coats the back of a spoon, you can run a finger down it and it stays separated.

Add the vanilla then the cold butter, one piece at a time, and whisk until incorporated before adding the next cube of butter.

Remove from heat and pass the lemon curd through a fine mesh sieve, if desired.

Pour the warm lemon curd into the cooled, baked tart shell and smooth the top of the curd with the back of a spoon.

Cover the tart with a sheet of plastic wrap and let cool in the fridge for at least 4 hours.

Make the Meringue

In a small saucepan over high heat with a candy thermometer attached, combine the granulated sugar and water, stirring only until it comes to a boil.

Once it reaches a boil, stop stirring. Cook until sugar syrup registers 240 degrees F (115 degrees C) on the thermometer.

While the syrup rises to temperature, combine the room-temperature egg whites, vanilla extract, and cream of tartar in the very clean bowl of a stand mixer fitted with the whisk attachment. Set mixer to medium-high speed and whisk until soft peaks form (the lifted whisk should form gentle peaks in the egg whites that very slowly collapse back into themselves) about 2-3 minutes.

When the sugar syrup comes to temperature, carefully and slowly drizzle in hot sugar syrup while the mixer is whisking at medium speed, avoiding the whisk in the bowl. Be careful. This hot syrup can burn you if you get it on you. Aim for a spot between the whisk and the side of the bowl.

Once all the syrup is added, increase the mixer's speed to high and whisk on high speed until the bottom of the mixer bowl is cool to the touch, 10 minutes.

Serving

Remove the plastic wrap from the cooled lemon tart.

Pipe or dollop the meringue onto the top of the lemon curd. If dolloping, use a spoon to make swoops and swirls for a more beautiful finish.

Use a culinary torch to gently scorch and brown the meringue.

Serve. The meringue is stable, it won't weep or deflate so you can decorate ahead of time.