Makes 5 to 6 dozen cookies
Note: These colorful cookies take on the pattern of whatever decorative glass, like a vintage water tumbler, you use to press them out. The bottom of a crystal bowl or vase works well, too.
Active time: 30 minutes
Total time: 1 hour
Preheat oven to 350°. In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugar until light and fluffy, about 2 minutes. Add yolks and vanilla, beat again to combine, and then beat in flour.
Form dough into 1" balls and arrange on large, ungreased baking sheets, spacing cookies about 2" apart. Transfer decorating sugar to wide, shallow dishes. Press 1 ball of dough with the bottom of a decorative patterned glass. Then dip the glass in sugar and flatten a cookie with it, so the pattern and sugar transfer to the top of the dough. Repeat with remaining cookies.
Bake until cookies are lightly golden around the edges, 10 to 12 minutes. Let rest on baking sheets 2 minutes, then gently transfer to baking racks to cool.
Adapted from The Food52 Cookbook, by Amanda Hesser and Merrill Stubbs (William Morrow).