- 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.