- In a bowl, combine the flour and salt. Set aside.
- In another bowl, combine the butter, sugar and ground almonds. Add the egg and mix thoroughly. Stir in the flour and form into a ball. Shape into a disc, cover in plastic wrap and refrigerate for 1 hour.
- Divide the dough into six pieces, roll each piece into a ½ cm (¼-inch) thick disc. With each disc of dough, line a 10 cm (4-inch) round and 2-cm (¾-inch) deep tart pan with a removable bottom. Refrigerate for 30 minutes.
- With the rack in the middle position, preheat the oven to 200 °C (400 °F).
- Bake for 15 minutes or until the crusts are golden brown. Let cool on a wire rack.
- In a saucepan off the heat, combine all the ingredients, except for the butter. Bring to a boil over medium heat, stirring constantly with a whisk, making sure to scrape the bottom of the pan and simmer for 30 seconds. Strain and let cool.
- In a blender or food processor, purée the cooled lemon curd and butter until smooth. Scrape a few times.
- Pour into the cooled crust. Cover the tarts with plastic wrap directly on the curd and refrigerate for about 2 hours or until the curd has set.
- In a bowl, beat the egg whites and cream of tartar with an electric mixer until soft peaks form.
- Gradually add the sugar, beating until stiff peaks form. Spread the meringue on the cooled tarts, covering the whole surface to the edge of the crust.
- Caramelize the meringue using a small culinary torch.