¼tspcoarse Kosher salt(if using table salt, use half the amount)
1tspground cinnamon
½tspground ginger
¼tspground cloves
¼tspground nutmeg
¼tspground allspice
¾cupcold unsalted butter,cut into tablespoons
1 ½tspvanilla extract
2tbspwhole milk
1tbsplight or dark molasses
Icing
½cuppowdered sugar
1tspmeringue powder
1 ½tbsplemon juice
Instructions
Make, Cut and Chill the Dough
In your food processor, measure the flour, powdered sugar, salt and spices. Pulse several times until well combined.
With the processor running, drop the butter down the chute, a tablespoon at a time, and process the mixture until moist and crumbly.
Add the vanilla extract, milk and molasses, and process just until the dough comes together into a dough ball.
Dump the dough out onto a clean counter and gather any dry floury bits together, shaping the dough into a disk, and lightly dusting it with a little extra flour.
Lightly brush a 9-inch square baking pan with a little soft butter, then line the pan with parchment paper. The butter will help keep the paper from sliding around, and the paper will allow you to easily remove the baked shortbread.
Press the dough into the pan in an even layer. Then cut the dough into "sticks" - this is easiest to do with a bench scraper. Be sure to dip the bench scraper in flour in between cuts. First cut the dough in half, then cut each half into 12 sticks, for a total of 24 cookie sticks that are 3/4 inch wide and 4 1/2 inches long.
Use a toothpick, skewer or cake tester to prick the dough all over - this is called "docking the dough", and helps prevent it from puffing up as it bakes.
Refrigerate the shortbread for 30 minutes.
Bake
Preheat the oven to 300 F, and position a rack in the center of the oven.
Bake the chilled shortbread for about 35 minutes, until the top looks golden brown and baked through.
Set the pan on a cooling rack, and immediately use your bench scraper to cut the shortbread again. Cool completely in the pan before removing the shortbread.
Icing
Set the cookie sticks on a cooling rack placed over a baking sheet.
In a small bowl, whisk together the icing ingredients until smooth and drizzly. Drizzle the lemon icing over the cookies, and let it set for about 30-60 minutes.
Store the baked shortbread in an airtight container at room temperature for 1-2 weeks, or in the freezer for up to 3-6 months.