This comes from that 80's classic, The Silver Palate Cookbook. They are sooo quick to make and soooo good!!
2 sticks (½ lb) butter, softened
1 C light brown sugar
1 egg yolk
2 C flour
1 tsp vanilla
2 C (12 oz) chocolate chips
1 C coarsely chopped walnuts or pecans
Preheat oven to 350°F. Grease and flour a 9" x 12" baking pan.
Cream butter and sugar. Add egg yolk and vanilla; beat well. Add flour. Mix well, then spread into prepared pan. Bake approximately 25 minutes, or until nicely browned.
Sprinkle chocolate chips evenly over cookie layer, then return to oven for 3 to 4 minutes.
Remove pan from oven and spread melted chocolate evenly. Sprinkle with chopped nuts. Let cool completely. Cut into 24 squares.