Cream the butter and sugar together. Beat in egg yolks. Whisk together flour, salt, and baking powder. Mix dry ingredients into the butter mixture. Divide dough into 2 disks. Wrap in plastic and freeze for 30 minutes.
Using a box grater, shred 1 disk into the bottom of your baking pan. Spread evenly with the jam. Grate the 2nd disk evenly on top of the jam layer. The dough might mound up over the top of the pan but it will settle in the oven.
Bake at 350 degrees for about 30 minutes or until evenly browned and set to the touch. Place on a cooling rack and cool at least 10 minutes. Sprinkle with powdered sugar and slice.