Dug up a recipe from my days in Finishing School. The cookies are named diamond because when rolled in coarse sugar they appear as they were rolled in diamonds.
1 cup (2 sticks) butter, chilled
2 ¼ cups flour
½ egg (try to get both the white and some yolk)
¾ cup powdered sugar
Dash of salt
½ teaspoon vanilla extract
Coarse decorating sugar (white or desired color)
1 egg white for brushing on the dough
On your work surface, cut the butter into the flour. Mixture should be the size of peas.
Form the mixture into a circle, and make a well in the center. Add egg, sugar, salt and vanilla to the center and mix together with your fingertips. Cut mixture into the flour and butter.
Line the dough in front of you. Using the heel of your hand, smear the dough away from you to shear the dough against the countertop to combine. Gather the dough together and repeat. The dough should be combined after two to three passes. Work quickly so you don’t heat and soften the butter.
Roll the dough into 2 logs, each about 1 inch in diameter. Wrap each log in parchment or plastic wrap and chill at least 1 hour.
Turn the logs every 15 minutes so the bottom does not get flat. If you have a rounded loaf pan, you can rest the dough on the pan so it will stay in a round shape. Or, place inside a paper towel roll.
When the dough is well chilled, preheat your oven to 350 degrees. Unwrap the dough.
Place a piece of parchment paper on your work surface, or use a large plate. Make a line of sugar the length of the dough, about ¼ to ½ inch deep and 2 to 3 inches wide. Brush the log with a thin layer of egg white, then roll in the sugar, pressing to adhere the sugar to the logs. Repeat with second log. If the dough feels soft, place in refrigerator 5 minutes.
Slice dough into ½- to ¾-inch slices and place about 1 inch apart on a parchment-lined baking sheet. Reshape as necessary so the cookies are round.
Bake in preheated oven 8 to 10 minutes until cookies are just beginning to brown. Remove from oven and cool. Store in an air tight container up to 1 week, or freeze.