Preheat oven to 325°F.

In food processor with knife blade attached, pulse flour and sugar until combined. Add butter and pulse until dough begins to come together. In medium bowl, with hand, gently knead in nonpareils or baking bits until evenly blended and dough forms a ball.

On lightly floured waxed paper, pat dough into 8” by 5” rectangle; freeze 15 minutes. Cut dough into 1/2-inch squares. Place squares 1/2 inch apart, on ungreased large cookie sheet.

Bake cookies 18 to 20 minutes or until lightly browned on bottom. Transfer cookies to wire rack to cool. Repeat with remaining dough. Store cookies in a tightly covered container at room temperature for up to 1 week, or in freezer up to 3 months.