Blend the almonds and both flours; set aside. With the paddle of an electric mixer (or regular beaters), cream the butter on medium speed until soft and creamy but not melted. Add the salt and confectioners’ sugar; mix on medium-low speed until thoroughly combined, about 5 minutes, scraping the bowl as needed. Reduce the speed to low and add the egg; mix until blended. Add the flour mixture; as soon as the dough comes together, stop the mixer. Scrape the dough onto a large sheet of plastic wrap. Using the wrap to help shape and protect the dough, gently press it into a rectangle that’s about 4-1/2 x 8 inches and about 1-1/2 inches thick. Wrap in plastic and refrigerate until dough is firm enough to slice, at least 3 hours.
Heat the oven to 400°F. Line a baking sheet with parchment. Unwrap the dough, trim the edges, and slice it into three 1-1/2-inch-square logs. Slice each log into square cookies between 1/8 and 1/4 inch thick. Lay the squares 1/2 inch apart on the baking sheet. Bake until lightly browned around the edges, about 8 minutes, rotating the sheet halfway through. Cool on the baking sheet until cool enough to handle (about 10 minutes) and then transfer the cookies to a rack.
nutrition information (per serving):
Photo: Mark Ferri