Preheat oven to 350°.
Cream butter and gradually add in sugar, mixing well.
Add eggs, one at a time, beating mixture well after each addition.
Combine flour, baking powder, and salt.
Add to butter mixture alternately with milk, beginning and ending with flour mixture.
Divide the batter in half.
Add remaining ingredients to one half of the batter, stirring until smooth.
Drop batter by Tablespoonfuls into a greased 9" x 5" x 3" loaf pan, alternating dark and light batter.
Bake at 350° for 1 hour or until wooden pick inserted into center comes out clean.