This is the best recipe for Hungarian shortbread ever! Filled with quince paste (or other jam), it is unbelievably crunchy due to the egg yolk in the dough. It can be made in advance and you'll need freezer space and a large-holed grater.
In a bowl beat 1 cup unsalted butter until light and creamy.
Add 2 egg yolks and mix well.
Add 1 cup sugar, beating a few minutes until almost incorporated.
Add 2 cups all-purpose flour, 1 teaspoon baking powder and ¼ teaspoon salt. Incorporate with a wooden spoon or spatula; it will be a tad sticky.
Divide into two pieces, and cover with plastic wrap. Freeze until hard but not rock solid, about 45 minutes.
Preheat oven to 375ºF (190ºC).
Line an 8-inch square pan with parchment paper. See Notes below.
Using a wide holed grater, grate one of the dough pieces, moving it around the pan as you grate, letting the strands cover the bottom of the pan. Press lightly to avoid holes or parts with no dough. Don't make it too compact.
Cover the bottom dough with 11 ounces quince paste, jam or preserves. If it’s too stiff, soften it with a few tablespoons of orange juice or water. Be careful not to tear the dough when spreading the filling. I put tablespoons of the paste in mounds and then spread it with the back of a spoon or an offset spatula.
Grate the rest of the cold dough, letting it fall as evenly as possible over the filling. Press very lightly if you want, but not much.
Bake for 15 minutes, turn the oven down to 350ºF (180ºC) and bake another 30 minutes or until it’s golden brown and dry.
Let cool on a wire rack, running a smooth-bladed knife around the edges while it's still hot to release stuck parts of paste or jam (if there are any).
Notes
Prepare the pan: line the greased pan with strips of parchment paper. When ready to cut and serve, they will help you remove the whole loaf. The strip (or strips) must be as wide as the pan. 1 strip: cover the bottom and two short sides. The two long sides will be greased but not lined. 2 strips: make a crisscross pattern and cover the bottom (twice) and all sides. One strip will be wider than the other.Baking time: consider that all ovens and pans are different, even if they look similar. The baking time in my recipes is as accurate as possible, but it might take you more or less time. You can use a thermometer to check that your oven is at the right temperature. I recommend tracking how your oven works and what tiny details you might need to adjust. Grater: Use a large or coarse-holed grater. Otherwise, the process will be messy.Freezing the dough: you can't skip this step if you want to achieve the right consistency.