In a bowl (or a food processor) mix the rice flour with the butter, eggs, sugar and baking powder, until the mixture is dense and uniform. Cover with plastic wrap or a tea towel and leave to rest in the refrigerator for half an hour. Then roll out the pastry and use it to line the tart molds, which you have previously greased. Fill with the hazelnut custard and Fabbri amarenas. Finish off by covering with little strips of the remaining pastry. Bake in a pre-heated oven at 180°C for 20 minutes.