A recipe submitted to Family Circle at one point and said to be Michelle Obama's. This version is the one made by the Ritz Carlton Hotel in Washington DC. There's another version floating around that's similar but calls for cake flour.
2sticksunsalted butter, softened (I recommend salted)(230 grams)**
1cupsugar(200 grams)
1largeeggseparated
1 ½tablespoonsAmaretto
¼teaspoonsalt (I'd probably use more like ¾ teaspoon)**
1teaspoongrated orange rind
1teaspoongrated lemon rind
2cupsflour(270 grams)
¾cupslivered almonds (sliced okay, too)
Instructions
Preheat oven to 300 degrees F. Have ready an ungreased 10x15 inch jelly roll pan. If you plan on transferring the shortbread to a different surface to cut it, you may want to line it with parchment paper.
With an electric mixer, beat the butter and sugar until smooth and creamy (about 3 minutes).
Add the flour ½ cup at a time and stir by hand until mixture is well blended.
Pat the mixture into an even layer in the pan. This is a much thinner shortbread than most.
Whisk the egg white until foamy, then brush on top of dough. Sprinkle with almonds.
Bake for 25 to 35 minutes until lightly browned.
Cool slightly and cut into two inch squares while still warm.
Yield: 40 squares
Notes
The recipe calls for 1 cup of unsalted butter and ¼ teaspoon of salt. I'd probably use salted butter and keep the ¼ teaspoon of salt or go with unsalted and increase the salt to at least ¾ teaspoon. I'll update when I test.