1. Prepare brownie mix as directed on the pkg.
Spread in ggreased 13x9 in baking pan.
2. Mix cream cheese, sugar, and vanilla with electric mixer on medium speed until well blended. add egg; mix well. Pour over brownie mixture; cut through batter with knife several times for a marble effect. Sprinkle with chips .
3. Bake at 350º for 35 to 40 minutes. or until cream cheese mixture is lightly browned. Cool in pan on wire rack. cut into squares.
Makes about 24 brownies