I posted a recipe for Scottish shortbread around the Holidays back in 2012. Since then I’ve been reading recipes that include rice flour so I thought I’d see if it makes any difference even though I couldn’t find any reason why.
I called my friend Shirley Corriher  to ask what the deal was for such an addition. She’s a biochemist and author of BakeWise and CookWise. She said it would make the shortbread more crisp. Sure enough it makes it lighter in texture and has a crisp snap when broken. However, by all means if you don’t have rice flour you can still make delicious shortbread .
1 cup (4 1/2 ounces or 130 grams) unbleached all-purpose flour
1/4 cup (1 1/4 ounces or 35 grams) rice flour
3 tablespoons (1 1/4 ounce or 35 grams) semolina flour
5 tablespoons (2 1/4 ounces or 60 grams) granulated sugar
1/4 teaspoon fine sea salt (*if using salted butter omit the fine sea salt)
1/2 cup (4 ounces or 115 grams) salted* or unsalted butter
1 teaspoon pure vanilla, optional
Preheat the oven to 325°F. Have handy a 7- or 8-inch cake ring, springform pan or removable bottom cake pan. If using a springform or cake pan, lightly butter the bottom and line with a round of parchment paper. If using a cake ring, set it on a parchment lined sheet pan.
Weight or measure the flours, sugar, and salt into a large bowl; whisk to combine. Cut the butter into 8 or 10 pieces and scatter on top of the flour mixture; pour the vanilla over the mixture as well, if using. Using your fingers, incorporate the butter and vanilla into the flour mixture until all the ingredients are completely combined and dough comes together when pressed.
Crumble the dough evenly around the prepared pan or cake ring. Firmly press the dough into the pan with your fingertips.
Prick the dough all over with a fork to prevent it from puffing and bake until the shortbread is golden, about 32 to 38 minutes.
Remove from the oven and cool it in the pan (or ring) for about 10 – 15 minutes on a cooling rack. If a cake pan was used, loosen the edges of the shortbread with a sharp knife and carefully turn it out onto a cutting board.
If using a cake ring, loosen and remove the ring while the shortbread is still warm and move to it a cutting board. Cut the round into 8 (or more) wedges using a serrated knife and set on a cooling rack. Store shortbread, well wrapped, for up to a week; freeze for longer storage.