Shortbread Crust: Preheat the oven to 400 degrees .
Working on a large flat surface, such as a pastry board, place flour, pecans and sugar in the center of the surface and mix together; form a small depression or well in the center of the mound.
Add the egg yolk and the softened butter to the well, then blend these with the dry mixture.
Mix the ingredients thoroughly using your hands -- there is no substitute for warm hands; shape the dough into a ball and wrap in plastic wrap and chill for at least 10 minutes.
Roll out the dough to a thickness of about 1/4-inch - You should have a circle of about 11 inches in diameter.
TIP: For best results, roll out your dough between 2 sheets of waxed paper, then peel away the paper and cut the crust in a 9 inch circle.
Place the circle inside a 9 inch springform pan; prick the crust several times with a fork to keep the crust from puffing up during the baking.
Place the springform pan in the oven and bake for 15 to 20 minutes, or until light brown; allow to cool.
Using the leftover dough, line the sides of the springform pan; press the dough against the sides of the pan, smoothing it so as to have a continuous layer of crust all the way around the sides of the pan - Make sure that the side crust meets the bottom crust all the way around.
Brush the reserved egg white onto the shell, covering the bottom and sides - this will seal the dough and keep it from becoming soggy; set aside until ready to use.
Cranberry Glaze Filling: Mix the sugar and cornstarch together in a small saucepan; stir in the cranberry sauce.
Cook over medium heat, stirring constantly, until thick; stir in the lemon zest and lemon juice, then set aside to cool slightly.
White Chocolate Filling: Reset the oven to 350 degrees; boil the orange juice and piece of orange peel in a heavy medium saucepan until the juice is reduced to 3 tablespoons - about 12 minutes.
Remove and discard the strip of orange peel and set aside the reduced orange juice.
Using an electric mixer, beat the cream cheese, sugar, grated orange zest, liqueur and reduced orange juice until smooth.
Beat in the melted white chocolate and then the eggs, one at a time, beating just until combined; pour the cranberry glaze filling into the prepared crust, spreading evenly.
Pour the white chocolate filling over the cranberry layer and bake about 50 minutes (the top will be dry and the sides puffed slightly - the center will not be set).
Move cheesecake to a wire rack and cool completely to room temperature; chill in the refrigerator overnight.
Candied Oranges Topping: Cover a wire rack with waxed paper; set aside.
Combine the water and sugar in a heavy shallow wide skillet; stir over medium heat until the sugar dissolves.
Simmer 5 minutes longer; add the orange slices 1 at a time and adjust the heat so that the syrup bubbles only around the edges of the pan.
Cook the oranges for one hour; turn over the top layer of oranges and cook until the oranges are translucent and the orange peels tender, about another one hour longer.
Lift and drain each orange slice out of the syrup, and arrange the slices in a single layer on the prepared rack; let dry 1 hour.
Boil the orange-sugar syrup until thick, about 6 minutes.
Loosen and remove the sides of the springform pan; set the cheesecake on a serving dish.
Overlap the candied orange slices around the top of the cheesecake.
Reheat the orange syrup, if necessary, and brush over the orange slices; drizzle any remainder over each serving.
Garnish: whipped cream
NOTE: You may substitute grapefruits for the oranges in the Candied Oranges Topping if you prefer.