1) Combine the sugar, butter, egg yolk, salt, and vanilla in a bowl, beating until smooth.
2) Add the flour, mixing until smooth. The mixture will seem dry at first, but will suddenly become cohesive. If it doesn't, dribble in a tablespoon of water.
3) Divide the dough in half, shape each half into a flattened disk, and wrap in plastic. Refrigerate for 2 hours, or overnight.
4) Remove the dough from the refrigerator, and let it soften for about 20 to 30 minutes, until it feels soft enough to roll. It should still feel cold, but shouldn't feel rock-hard. If dough softens too quickly, return to refrigerator.
5) Sprinkle your rolling surface with flour, and flour your rolling pin. Working with one piece of dough at a time, roll it 1/8" to 3/16" thick.
6) Use a linzer cutter to cut a base and a cutout top for each cookie. It's good to cut them in pairs so you know you have an even number of each. Re-roll and cut the dough scraps.
7) Place the cookies on ungreased or parchment-lined baking sheets. They can be close together; they'll barely spread.
8) Bake the cookies in a preheated 350°F oven for 12 to 14 minutes, until they're set and barely browned around the edges. Remove from the oven, and cool right on the pan.
9) To create the beautiful white sugar tops, fill a fine sifter with confectioners' sugar. Hold the sifter a few inches above the cookie and shake or tap the sifter to drift sugar onto the cutout piece of the cookie. Be sure to cover the cookie with an even layer, all the way to the center and edges.
10) On the solid base of the cookie, spread 1/2 teaspoon of your favorite filling or jam (apricot, raspberry, strawberry, chocolate, or even icing). To complete the cookie, place the sugared top gently on the filled base and press together.
11) It's best to let these cookies sit for a few hours to let the "sandwich" set. Overnight is fine as well; just cover the cookie tray with plastic wrap.
Yield: 3 dozen linzer cookies.
You can really use any size you like, but the standard would be around a 1.5-2" diameter shape for the base and then a cut out of whatever size you would like in the center. Happy Baking! Jocelyn@KAF