This is a food processor recipe because that's the fastest, easiest way to make these. If you don't have one you could grind the sugar and nuts in your blender and fold the rest of the ingredients together by hand. Do not attempt to move these cookies off the sheet trays until they are entirely cool as they are extremely fragile and will break on you. (if this happens just consider them a chefs snack) This recipe is an adaptation of two recipes: Mexican Wedding Cakes by Rose Levy Beranbaum and Russian Tea Cakes by Betty Crocker. With those two as sources, how could these be anything but delicious?
Butter Flats
1 cup walnut halves
1 cup powdered sugar
1/4 teaspoon salt
8 ounces cool, diced butter
2 cups AP flour
4 tablespoons powdered sugar for dusting
Pulse the walnuts, 1 cup of powdered sugar and salt in the food processor until the mixture has the texture of fine breadcrumbs. Add the butter and process until smooth and well blended. Add the flour all at once and pulse just until the mixture forms a cohesive dough. Scrape the dough out into a small bowl, cover with plastic wrap and chill for at least one hour and no more than three hours. If you do chill it for longer than three hours, let it sit at room temperature for at least 45 minutes before using.
Form 1.5 inch balls using either your hands or an ice cream scoop and lay them out on a cookie sheet with at least 2 inches between each cookie. I use half sheet trays and can lay them out 3X5 on the tray. Bake at 350 degrees Fahrenheit for 8-10 minutes, rotating once until just set and golden around the edges. Dust with powdered sugar and let cool for at least 15 minutes before removing from the trays. Makes approximately 30 2-inch cookies.
They will probably keep for up to a week in a tightly sealed container. I can't say for sure because mine were gone in a matter of days.