Prepare brownie mix batter according to package directions. Spread 2 cups into a greased 13x9-in. baking dish; set aside., In a small bowl, beat the cream cheese, butter, sugar, flour and vanilla until smooth. Add eggs; beat on low speed just until combined. Spread evenly over brownie batter. Top with remaining brownie batter. Cut through batter with a knife to swirl., Bake at 350° for 28-32 minutes or until a toothpick inserted in the center comes out with moist crumbs (brownies may appear moist). Cool completely on a wire rack. Spread frosting over brownies.