Chocolate Chip Butter Cake

8 oz Butter or Margarine
2 c Sugar
4 Eggs, separated
2 2/3 c Sifted Cake Flour
2 ts Baking Powder
1/2 ts Salt
1 c Milk
2 ts Vanilla
5 oz German Sweet Chocolate Bars Cream butter and sugar together.
Add yolks one at a time, beating well after each addition.
Add sifted dry ingredients, alternating with milk and vanilla.
Add in thirds, beating until smooth after each addition. Grate chocolate coarsely, reserving 1/3 cup for the topping. Beat whites until stiff and fold into batter, add remaining chocolate to batter and mix. Pour in a greased and floured 9x13 pan. Sprinkle the top with the 1/3 cup of grated chocolate. Bake in a preheated 350 degree F oven for 40 minutes.