Melt
butter and 2 cups chocolate chips together.
In
a small bowl mix flour and baking soda together.
Put
melted chocolate mixture in a large bowl. Add sugar
and beat for about 5 minutes until smooth. With mixer
on add vanilla, and gradually add water. Add eggs one
at a time and beat after each addition.
With
mixer on low add flour mixture until blended. Fold in
remaining 1 cup semi-sweet chocolate chips and white
chocolate chips.
Pour
into a greased 9 x 13 inch pan. Bake at 325 degrees
F. for 35 to 45 minutes. Cool. Cut into squares. Store
in refrigerator.