The evening before, prepare the pastry: Mix flour, 1 tablespoon of sugar, salt and grated orange skin. Add butter and mix. Beat the egg and add, kneading it in as quickly as possible. If needed add a little water. Make a bowl, wrap it in cellophane paper and leave inside refrigerator. -Next day: Take wedges out of the oranges. Take off thin skins and discard. Drain. Chop the hazlenuts finely. In a bowl, mix eggs and thickening agent, sugar, fresh cream, jam and hazlenuts. Carefully add the the orange wedges. Leave inside refrigerator. Divide the pastry into two parts, one made up of two thirds, the other one of one third. Let rest at room temperature for 1 hour. Pre-heat oven to 180 degrees Celsius. Make 4 circles with the first two thirds about 5 mm thick and spread them inside tart molds leaving the pastry coming over the brim. Stab pastry with a fork. Keep inside refrigerator for 30 more minutes. Take out of refrigerator. Fill tarts with the orange cream up to two thirds of its depth. Make 4 circles with other third of pastry wide enough to be slightly wider than the molds. Place one circle on top of each tart/pie and secure it by pinching both pastries together. Make a small hole in the middle and insert a small cone of baking paper inside. Bake for 20 minutes. Take out of oven. Beat the egg yolk with 2 tablespoons of water and brush the whole top of the pie. Sprinkle with a little sugar and bake again for 10 minutes. Serve lukewarm.