Cardamom Shortbread Cookies

Makes about 3 dozen bar cookies.
For dough
2 cups flour
2 teaspoons ground cardamom
¼ teaspoon salt
1 cup (2 sticks) unsalted butter, at room temperature
½ cup granulated sugar
½ cup light brown sugar
1 egg, separated
1 teaspoon vanilla extract
1/3 cup chopped nuts
For icing
1½ tablespoons butter, melted
½ teaspoon vanilla extract
1 cup powdered sugar
Milk as needed
Candied fruit, if desired, for garnish
Directions
To prepare cookies: Preheat oven to 275 degrees.
In a medium bowl, whisk together flour, cardamom and salt, and reserve.
In a bowl of an electric mixer on medium-high speed, beat butter until creamy, about 1 minute. Add granulated sugar and brown sugar and beat until light and fluffy, about 2 minutes. Add egg yolk and vanilla extract and beat until thoroughly combined. Reduce speed to low, add flour mixture and mix until just incorporated. Spread dough into an ungreased 9- by 13-inch baking pan. Brush egg white over dough, sprinkle evenly with chopped nuts and bake for 1 hour. Remove from oven and transfer pan to a wire rack to cool.
To prepare icing: In a bowl of an electric mixer on medium speed, beat melted butter, vanilla extract and powdered sugar until creamy. Add milk, 1 teaspoon at a time, until icing reaches drizzling consistency. Spread icing over slightly warm bars and garnish with candied fruit (optional). Allow icing to set and cut bars into cookies while bars are still slightly warm.
2005 Finalist: Alecia Enger of Hudson, Wisconsin