Butter Walnut Cookies

Dough :
2 1/2 cubes unsalted butter (20 Tbsp)
2 cups all-purpose flour
1/8 tsp salt
Grated peel of 1 lemon
1 whole egg
3 egg yolks
1 Tbsp sugar

Topping :
1 cup walnuts very finely chopped
1/4 cup granulated sugar
About 2 egg whites
Powdered sugar

1. Prepare the dough as you would a pie crust: Cut the butter into pieces and mix with the flour and salt; use hands as little as possible so the dough won't get warm.

2. Combine the lemon peel, egg, egg yolks (saving whites for topping) and tablespoon of sugar. Work into the flour. Pull the dough together, wrap in plastic wrap and refrigerate several hours or overnight.

3. To prepare the topping: Combine the walnuts and sugar; set aside.

4. Preheat oven to 375 degrees (F). Roll out half the dough at a time to about 1/8-inch thickness on a floured surface, or between sheets of floured plastic wrap. Cut with cookie cutters in desired shapes. Place on ungreased baking sheets. (Or line baking sheets with parchment paper for easier clean-up.)

5. Brush tops lightly with egg white. Spoon the walnut mixture on top, pressing down lightly. Bake on center oven rack 10 to 12 minutes, or until golden brown. Cool 10 minutes before transferring to racks. Dust the cookies with powdered sugar before serving.

Makes about 7 dozen.