Put flour, fat in flakes, sugar, egg, salt and lemon zest in a bowl. Work through to a smooth dough with the dough hooks of the hand mixer. Wrap the short pastry in foil and chill for about 30 minutes. Stone dates, cut the fruit flesh into fine cubes. Beat egg white until stiff, add sugar. Fold in dates.
Roll out short pastry on a floured work surface to a thickness of approx. 1/2 cm and cut into squares (5 x 5 cm). Use a teaspoon to spread some macaroon mixture on the shortcrust pastry squares. Place opposite pastry squares on top of each other in the middle. Brush with egg yolk and bake in the preheated oven for 40 minutes (electric oven: 150 °C/ gas: level 2). Let them cool down on a cake rack
Preparation time approx. 1 hour (without waiting time)