How to Make It
Soak the quinoa in water for 10 minutes, then drain.
Beat together the butter and sugar using with an electric mixer until combined. Add the egg and vanilla, then beat to combine. Stir together the flour, baking powder and salt, then beat into the butter mixture just until combined. Stir in the quinoa.
Wrap the dough in plastic wrap, flattening into a disk, then chill 30 minutes. Preheat the oven to 350°F.
Roll the dough out to 1/4-inch thick on a lightly-floured surface, then cut 1 1/2-inch rounds or squares, and transfer them to two baking sheets. Bake the cookies until they are puffed and golden on the bottom, 10 to 12 minutes. Let cool then serve.