1 cup unsalted butter
1/2 cup granulated sugar
1/2 cup brown sugar, firmly packed
1 large egg, separated
1 teaspoon vanilla extract
2 cups all-purpose flour
1 1/2 cups semisweet chocolate chips
3/4 cup chopped nuts
Preheat oven to 375°F.
In a mixing bowl, cream together butter, granulated sugar and brown sugar until light and fluffy. Add egg yolk and vanilla; mix well. Stir in flour.
Pat mixture into an ungreased 13 x 9 x 2-inch baking pan. Brush with egg white. Bake for 25 minutes or until light brown. Cool for 5 minutes.
Sprinkle with chocolate chips and when soft, spread over the top. Sprinkle with chopped nuts, lightly pressing them in. Let stand until firm; cut into 16 equal bars when firm.
Makes 16 bars.