Preheat oven to 350°F.
Lightly grease a 13 X 9 inch pan.
Cream butter, granulated sugar and 1/4 cup of the brown sugar in large bowl.
Beat in egg yolks and vanilla.
Combine flour, baking powder, baking soda and salt in small bowl.
Blend into creamed mixture.
Stir in enough milk to make a smooth, light dough.
Press on bottom of prepared pan.
Sprinkle chocolate chips over the top; press them down lightly into dough.
In clean, dry bowl, beat egg whites until stiff, but not dry.
Gradually beat in remaining 3/4 cup brown sugar.
Spread mixture evenly over dough in pan; top with peanuts.
Bake 25 to 30 minutes or until top is puffed, lightly browned and feels dry.
Cut into 2 X 1-inch bars while still warm.