In the mixing bowl of a stand mixer, sift all-purpose flour, almond flour, powdered sugar, and salt. Add cold butter.
Using a pedal attachment, mix all ingredients. Add egg and mix again until it has a “sand-like” consistency.
Place dough between two parchment papers and roll it to 1/8 inch thickness. Transfer parchment paper with the dough to the baking sheet pan. Chill the dough in the freezer for at least 2 hours.
Take the dough out of the freezer and remove the top parchment paper. Using the knife, cut the long strips out of the dough. Using perforated tart rings, cut the circles out of the dough. Carefully place the strips into the ring. Press the strip onto the ring and cut the strip if it is too long.
Chill tart rings with the shaped tarts in the freezer for one hour. Preheat oven to 320°F. Using a knife, trim the top of the tart.
Bake tart crust at 320°F for 20 minutes. Let tarts to cool at room temperature, then remove tart rings.
How to Make Lemon Filling
Place sugar, egg yolks, lemon juice, and lemon zest in a heatproof bowl over a saucepan of simmering water (double boiler) and cook over medium heat. The temperature of the mixture should reach around 80 °C (176°F).
Remove it from the heat and pour the cooked curd through a sieve.
Let it cool for a few minutes, then add butter. The butter will melt from the heat of the mixture.
Cover with the plastic wrap directly on top so it is touching the top of the filling, and refrigerate until use.
How to Make Meringue
In the mixing bowl of a stand mixer, add sugar and boiling water. Let it cool, and make sure the sugar is dissolved.
Add meringue powder and whip until stiff peaks. Transfer the meringue into a pastry bag with a piping tip.
How to Assemble Lemon Meringue Tart
Remove tarts from refrigerator.
Pipe meringue on the lemon filling. You can cover the whole tart or just a half of it. Use a kitchen torch to toast the meringue topping, optional.
Refrigerate until ready to enjoy.
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Notes
Use good quality butter. I used unsalted butter, but salted will also work.A tart crust can be made in advance and frozen for a few months. Make sure you are using an air-tight container for freezing.Use different piping tips for the meringue.