In a large saucepan melt together the sugar, butter, vanilla and water until the sugar has dissolved, then cool a little.
Place the flour, baking powder and salt into a bowl and make a well in the centre. Pour the wet ingredients into the dry and stir to form a slightly sticky dough.
Roll out to 2-3mm thick between two sheets of baking paper and place in the fridge to chill.
Meanwhile, melt and, if possible, temper the chocolate and fill the moulds (or make rectangular shapes on baking parchment). Leave to set.
cut or stamp out shapes. If you don't have a petit beurre stamper (which is probably unlikely!) prick each shape with a fork and transfer to a baking sheet.
Bake at 180 degrees for 10-12 minutes, until the biscuits are starting to turn golden around the edges. Cool on a wire rack.
Once cool, attach the chocolate stamp with a smear of melted chocolate.