Step 1Whisk together the yolks and cream in a bowl and set aside. In the large bowl of an electric mixer, using the paddle attachment, combine the flour, sugar and salt on low speed.
Step 2Add the cold butter and mix until dry and mealy with no large butter pieces, about 2 minutes. With the mixer on low speed, slowly pour in the cream mixture and mix just until dough comes together.
Step 3Pat the dough into a flat disk, wrap in plastic and chill 2 hours.
Step 4Heat the oven to 350 degrees. Roll out the tart dough about one-eighth inch thick and line 6 (4-by-1 1/4 -inch) individual tart pans with removable bottoms with dough. (You may substitute a 9-inch pie plate if tart pans are not available.) Trim the excess dough. (Reserve extra dough for another use.) Chill in the refrigerator or freezer at least 30 minutes.
Step 5Remove the tart shells from the refrigerator. Check for any holes and patch them with leftover dough. Line each tart shell (or the pie shell) with parchment paper and baking beans and bake the tart shells until the rims have begun to color, 10 to 12 minutes (15 minutes for a pie shell). Remove the beans and parchment paper and again patch any holes that might have appeared. Bake until the bottom of the crust is a light golden brown, 5 to 10 minutes (about 15 minutes for the pie shell).
Step 1Peel the potato and trim the ends and sides to make a rectangular block. Cut the potato into small dice.
Step 2Bring a pot of salted water to a boil. Measure one-half cup of the potato cubes and add them to the water. When the water returns to the boil, reduce the heat to a low simmer and cook until the potato is cooked through but firm, 4 to 5 minutes. Drain and reserve.
Step 3Heat the butter in a small pan over medium heat. Add the onion and cook until clear and soft, about 5 minutes.
Step 4Remove the pan from the heat and stir in the creme fraiche, potato, Morbier and Parmesan, being careful not to break up the potato cubes. Set aside to cool 10 minutes.
Step 5In a separate bowl, whisk together the eggs and heavy cream and gently stir into the potato and cheese mixture. Add the salt and pepper.
Step 6Spoon about one-fourth cup of the mixture into each pre-baked tart shell, enough to cover the bottom by one-half inch (or spoon half the mixture into the pie shell).
Step 7Place a slice of ham on the work surface and pinch the slice in the middle to make a bow-tie shape. Place the bow in the center of each tart, allowing the ham edges to hang off the side (or arrange 6 bow-tie slices around the pie). Spoon the remaining filling on and around the ham; you don't want to cover the slices completely.
Step 8Cover tarts loosely with aluminum foil (do not cover if using a pie shell) and bake at 350 degrees for 20 minutes. Remove the foil and continue baking until the filling is just set and the top is golden brown, 35 to 40 minutes (longer if necessary for a pie shell). If the ends of the ham begin to brown too much, cover them loosely with thin strips of foil. When the tart is cooked, parts of the ham should appear through the melted cheese. To serve, remove the quiches from the tart pans by placing a slightly cooled pan on top of a bottle and pushing down. Remove the rim and bottom of the pan and place each quiche on a plate.