Directions:

Prepare brownie mix as directed on package. Pour into greased 13x9 inch pan. Mix cream cheese, sugar and vanilla with electric mixer on medium speed until well blended. Add egg; mix until blended. Pour over brownie mixture; cut through batter with knife
for marbled effect. Bake at 350 degrees for 35-40 minutes or until mixture is slightly browned. Cool and cut into squares.