Grate half of the frozen shortbread dough into a baking dish without packing it down.
Spread the jam of your choice on top of the grated dough.
Grate the second half of the dough onto a sheet of parchment and scatter it over the jam.
Bake the bars until the shreds of dough have melted and formed a pebbly surface.
Dust the bars with powdered sugar before serving.
NOTES:
Streaked through the center with a layer of sweet-tart jam, these shortbread bars are made from dough that’s frozen (for up to a month!) and then grated right into the pan.
The dough is divided into two pieces and frozen solid—you can freeze the dough for up to a month, in case you’d like to get ahead on your holiday baking.
When you’re ready to bake, grate half the frozen dough directly into a baking dish. Remember, though you might be tempted, Polzine stresses: Don’t pat it down. But do scatter the dough strands gently around, if necessary, to even out the bottom layer.
Use an offset spatula to spread your jam of choice from end to end. Then, grate the second piece of dough onto a sheet of parchment (so that you don’t accidentally mash down the box grater or tire of holding your paddle aloft and mar the first two layers) and gently scatter the top layer of grated dough over the jam.
For a quicker cookie, Polzine says that you can use the grater attachment on a food processor to shred each portion of dough just before sprinkling it into the pan.
