Preheat oven to 325°. Grease 13 x 9? baking pan and set aside. In large bowl, beat 1/2 cup brown sugar, 1/2 cup sugar and butter until creamy. Beat in egg yolks and vanilla extract. Gradually stir in flour and baking soda until crumbly. Press dough onto bottom of greased 13×9-inch baking pan. Sprinkle evenly with chocolate chips.
Beat egg whites in medium bowl until soft peaks form. Gradually beat in 1/4 cup brown sugar and 1/4 cup sugar until stiff peaks form. (Actually, I?ve never been able to get the egg white mixture stiff; if you are beating and beating and stiff peaks won?t form, don?t worry about it. Just continue with the recipe; it will be fine.) Spread meringue over chocolate chips. Bake for 30 to 40 minutes or until top is set and lightly browned. Cool in pan on wire rack for 20 minutes. Cut into bars while still warm. Makes 36 bars.
These delicious layered bar cookies have a soft brown sugar crust, melting chocolate chips, and a brown sugar meringue crisp top. Yum.