Grease 4 tartlet tins (with removable bases) with butter, and chill. Knead together the flour, butter, sugar, salt and egg yolk. Wrap the dough in foil and refrigerate for approx. 3 hrs. Preheat oven to 200°C.
Cut the dough into 4 parts and roll out into circles of approx.18 cm . Place the dough circles into the tins and cover with baking paper. Pour in baking beans. Bake for 15 min., plus a further 5 min. without the baking beans. Leave to cool.
Warm the milk and cream in a pan. Soak the gelatine for 4 min., crush, and dissolve in the hot creamy milk. Cut the marzipan loaf into pieces and add to the pan. Blend with a hand-held blender. Stir in the vanilla sugar. Leave the cream to cool slightly, then pour into the tartlet tins. Chill for at least 6 hrs.
Remove from tins. Scatter the bilberries over the tartlets. Mix the juice, sugar and cake glaze in a pan and bring briefly to the boil. Spoon this mixture over the berries.