Butter, brown sugar, and Irish whiskey team up in this dough, which we give a long, slow bake. The result is a complex shortbread that ages to an even deeper flavor.
Lightly grease two 8˝ round pans, or lightly grease and flour a shortbread mold.
In a large bowl, beat the butter until smooth. Beat in the sugar, salt, and whiskey (or vanilla) until smooth. Mix in the flour and rice flour.
Divide the dough in half (each half will weigh about 11 ounces). Form each half into a 7˝ disk, then wrap and chill for 1 hour.
Preheat the oven to 325°F.
Unwrap the dough and press it into the prepared pans (the mold uses half of the dough at a time). Prick the dough all over with a fork to prevent it from puffing.
Bake for 32 to 38 minutes, until the shortbread is golden brown. Check at 18 minutes; if the shortbread is puffing up, use a spatula to press the dough down. Continue to bake until golden.
Remove the shortbread from the oven and let it cool for 15 minutes, then loosen the edges before turning over onto a cutting board. Tap the bottom of the pan to release the shortbread.
Cut each round into eight wedges using a serrated knife.
Store shortbread, well wrapped, for up to a week; freeze for longer storage. The flavor improves as the shortbread ages.
