Boil the milk with half of the sugar, the lemon rind, vanilla and a pinch of salt. Beat the remaining sugar in a bowl with the egg yolks and add the flour. When you have removed the lemon rind, add the milk. Place on the heat and stir with a whisk until the mixture comes to the boil, and keep stirring on the heat for about one minute. Lower the heat and continue stirring until the custard has reached the desired consistency. If you wish, you can add a knob of butter once you have taken the custard off the heat.
Remove the butter from the refrigerator and leave it to soften at room temperature. Make a well in the flour on the worktop and put the sugar, butter cut into little pieces, egg yolk, lemon rind, vanillin and a pinch of salt in the centre. Knead into a dough without handling the mixture too much, to ensure that the dough does not get warm (rinse your hands in cold water if necessary), until all the ingredients have been mixed in uniformly.Shape the dough into a ball and dust it with a bit of flour. Then wrap it in a cloth and leave to rest in the refrigerator for about half an hour. Before using the dough, roll it out with a rolling pin lightly dusted with flour. Bake in a pre-heated oven at 180° C for 20 minutes.
Using a whisk, mix the egg yolks with the sugar in a bowl, until the mixture is smooth and frothy. In another bowl, whisk the egg whites with a pinch of salt, and then blend them carefully into the beaten egg yolks, stirring gently from top to bottom. Sieve the flour with the starch and vanillin, and then add to the mixture, taking care to avoid lumps. Add the lemon rind and stir in gently. Then pour the mixture into a 26cm round cake tin, which you have previously greased and floured (or lined with greaseproof paper). Smooth the surface and bake the Sponge Cake in a pre-heated oven at 170° for 40 minutes.
Composition of the dessert
Line a 4cm mold with shortcrust pastry (2cm thick). Add a layer of custard, and place a sponge cake disc on top (about 1cm high).Add the Amarenas, followed by another layer of custard, and then cover with shortcrust pastry. Bake in a pre-heated oven at 170°C for about 35 minutes. Leave to cool, dust with icing sugar and decorate with Amarenas.