sift together dry ingredients; set aside

in large bowl, beat butter and brown sugar until combined.

add eggs one at a time

beat in vanilla and chocolate.

mix in sour cream and dry ingredients until combined

stir in boiling water

bake in greased 9X13 pan at 50 degrees F for 35 minutes. let cool

in bowl, beat butter until soft. add sugar and beat until fluffy. add vanilla and chocolate, and mix together