I bought my rice flour at Uwajimaya in Seattle but you can purchase it at any Asian grocery store. Only partially substitute this flour for all purpose. It adds a delicate crunch to cookies.
I made 1 1/2 recipes and so I used 6 sticks of butter! It was a lot of butter for not very many cookies.
Here is my secret for rolling out dough. I put the blob of dough between 2 large pieces of parchment paper and roll it out that way. No extra flour is needed - which can dry out or toughen a cookie. Then, I slide the rolled out dough, parchment & all onto a cookie sheet and place it in the fridge or the freezer to cool. After it hardens a bit, I take out the cookie sheet, loosen the parchment on both sides by peeling it off and then start cutting with my cookie cutter. The dough is so easy to handle when it's slightly hardened. If the dough gets frozen, I let it soften a bit before cutting.
Since the dough is hardened, I can pop the cut shape right out of the cookie cutter with my hands & place it on the prepared cookie sheet.
Hearst Castle Shortbread
4 cups all purpose flour
1/2 teaspoon baking powder
3/4 teaspoon fine grain sea salt
1 pound unsalted butter (4 sticks)
1 cup powdered sugar
1/2 teaspoon vanilla extract
Preheat oven 350%
Sift flour, baking powder & salt into bowl - set aside
In a mixing bowl, beat butter until light & fluffy. Add powdered sugar & keep beating. Beat in vanilla. Add the flour mixture slowly. Keep mixing until everything comes together in a thick dough.
Chill dough. (See my note above about rolling out dough). Roll out to desired thickness & cut with cookie cutter. (I roll out to between 1/4 - 1/2 inch thick). Place cut cookies onto parchment or silpat lined cookie sheet. Bake for 7-10 minutes or until the edges are lightly golden.