Prepare the Shortbread -Sift together flour, salt and baking powder; set aside.
With mixer on high, cream butter until light and fluffy. Next add egg yolks and 2 cups sugar. Mix until sugar is dissolved and mixture is light.
Switch mixer to low and add dry ingredients previously set aside. Mix only until incorporated. Make 2 balls, wrap in plastic wrap, and freeze 30 minutes.
Prepare the Jam - In a medium saucepan over medium heat, combine cranberries, orange juice, 1 cup sugar and orange zest. Simmer stirring often until cranberries are softened. Remove from heat. Let cool.
Assemble the Shortbread -Preheat oven to 350 degrees.
Using one ball, grate with coarse grater into 9 x 12-inch pan. Press down lightly. Cover with jam. With second ball, repeat with grater.
Bake for 40 minutes. Remove from oven and sprinkle liberally with powdered sugar. Let cool 10 minutes before cutting
