For the dough: Combine the flour, salt and sugar, make a well in the center, sprinkle the chopped butter around the edges and add the egg to the well with 50 ml (approximately 1/4 cup) lukewarm water. Chop all of the ingredients together with a knife until crumbly then quickly knead with your hands until smooth. Shape into a ball, wrap in plastic wrap and chill for 30 minutes.
For the filling: Rinse the cranberries and bring to a boil with the sugar and 4 tablespoons water. Reduce the heat and simmer for 3-4 minutes. Whisk the brandy and cornstarch until smooth then stir into the cranberries. Bring to a boil and cook until thickened.
Roll out the dough between 2 sheets of parchment paper until about 4-5 mm (approximately 1/8-1/4 inch) thick. Grease the tartlet pans with butter and line with the dough, trimming the edges. Line with parchment paper, fill with dried beans and blind bake in a preheated oven (200°C) (approximately 400°F) for about 10-12 minutes. Remove the beans and parchment paper and let cool.
Fill the tartlets with the cranberry filling and let cool.