Make sure the butter is soft before starting. Put the pecans in a food processor fitted with the metal blade and let the machine run until they’re pulverized. Remove the blade, transfer the ground nuts to a large bowl, and add the quinoa flour, baking powder, and salt. Stir to combine.
Return the blade to the food processor. Add the butter and sugars and pulse, scraping down the bowl every now and then, until the mixture is light and fluffy, about 3 minutes. Add the eggs and let the machine run until they’re fully incorporated and get a little fluffy, about 2 more minutes. Remove the blade and use a soft spatula to scrape the wet mixture into the bowl with the dry ingredients. Use your hands or the soft spatula until a crumbly dough forms that holds together when pressed. Divide the dough in half.
Tear off two pieces of parchment paper about 12 inches long. Working with one piece of dough at a time on a clean work surface, shape the dough into a log about 2 inches across; enclose it tightly in the parchment paper, tucking in the ends. Repeat with the remaining dough and paper. Put the wrapped logs in an airtight container and refrigerate until firm, at least 2 hours.
When you’re ready to bake, heat the oven to 400°F and get a wire rack handy. Lightly grease 2 baking sheets with the remaining 2 tablespoons butter. Slice the logs into cookies about 1/2 inch thick and divide them among the cookie sheets; you’ll probably have to work in batches. Bake the cookies until they’re browned on the bottom and around the edges but still soft when pressed in the center, 10 to 15 minutes. Carefully transfer the cookies to the wire rack as soon as they come out of the oven and cool completely before topping or glazing.
—Recipe developed by The Bittman Project for Bob’s Red Mill