In a bowl, mix the egg yolks, sugar and grated lemon zest. Add flour and yeast, then the butter. Mix everything and knead until you get a smooth dough. Roll out the pastry in a cake pan coated with butter and dusted with flour. Spread the marmalade on the pastry. Peel the oranges and remove all the white pith. Divide into segments and put the segments over the marmalade covered pastry arranging them in a fan-like shape. Sprinkle with confectioners' sugar and bake it in an oven at 180°C for about 25 minutes.