These sweet and nutty shortbread cookies would be perfect with an afternoon cup of tea. Martha made this recipe on Martha Bakes episode 607.
Whisk flours, salt, and chopped pecans in a bowl.
In the bowl of an electric mixer fitted with the paddle attachment, beat butter and sugar on medium-high speed until smooth and light, about 1 minute. Add maple syrup, egg yolk, and vanilla; beat on medium until well combined. On low speed, gradually add flour mixture; beat until just combined. Dough should be smooth and pliable. Flatten into a square. Wrap in plastic; refrigerate until firm, 1 1/2 hours or overnight.
Preheat oven to 275 degrees. Line a baking sheet with parchment paper.
On a lightly floured work surface, roll out dough into a 1/2-inch-thick rectangle. Cut out squares using a 3-inch fluted square cutter; place 1 inch apart on prepared baking sheet.
Bake cookies, rotating sheet halfway through, until golden just around the edges, 1 hour to 1 hour and 15 minutes. Transfer to a wire rack to cool. Cookies can be stored in an airtight container at room temperature up to 4 days.