Knead 250 g butter in flakes, icing sugar and flour first with the dough hooks of the hand mixer, then with your hands to a shortcrust pastry. Wrap the dough in foil, chill for about 1 hour.
Roll out the dough in portions on a floured work surface to a thickness of about 1 cm. Cut out a total of about 40 circles (Ø 5 cm). Knead the remaining dough again and again and roll out again.
Place the cut-out circles on baking sheets lined with baking paper. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 7-10 minutes one after the other, remove from oven and let cool on a cake rack.
Coarsely chop the cream toffees and melt them with the remaining butter in a saucepan over a low heat. Stir the melted caramel with a whisk until smooth and, while still warm, place it on the biscuits as a circular biscuit so that a biscuit edge is still visible. Let the caramel cool down for about 10-15 minutes.
In the meantime, roughly chop whole milk chocolate and melt it over a water bath. Allow the chocolate to cool and spread as cool as possible, but still fluid, as a clinker on the caramel glaze. Let the chocolate dry.