Roll out the shortcrust pastry with a rolling pin and use it to line the little tart molds. Cream the butter and sugar together with a pinch of salt, add the beaten eggs and continue stirring. Add the 00 flour and the coconut flour and mix with a spatula. Finally, add 2 or 3 spoonfuls of Barley syrup. Pour this custard mixture into the tart molds and place a slice of pineapple on top of each one. Use a spoon to remove the excess custard from the centre of each pineapple slice (you can leave a thin layer as a base) and fill the hole with 3 amarenas. Bake in a pre-heated oven at 160/170° C for about 20/25 minutes. Remove from the oven, leave to cool and brush the tarts with a layer of gelatin for cakes to make them shiny.