In a bowl or the bowl of your stand mixer, combine the sifted flour, icing sugar, almond flour, and salt.
Mix with a wooden spoon or the paddle attachment.
Add the softened butter, cut into pieces.
Mix with your fingers or the paddle attachment of your stand mixer.You should get a grainy, sand-like texture. Then add the egg.
Continue mixing until you get a smooth dough.
Form the dough into a ball and wrap it in plastic wrap to prevent a crust from forming.Refrigerate for at least 1 hour. Remove the dough from the refrigerator fifteen minutes before use to soften it, make it easier to roll out, and prevent it from breaking.
Using a rolling pin, roll out your dough on a floured work surface or parchment paper.You can lightly flour your dough if necessary. Place it in a tart pan or pastry ring. Prick the bottom with a fork.
You can then blind bake it or fill it and bake for about 25 minutes at 180°C/350°F.