Cover bottoms of 2 (9-inch) round pans with waxed paper; spray with cooking spray. Prepare cake batter as directed on package; blend in chocolate and food coloring.
Pour into prepared pans.
Bake 22 to 25 min. or until toothpick inserted in centers comes out clean. Cool 10 min.; remove to wire racks. Cool completely.
Toss berries with 2 Tbsp. sugar; set aside. Beat cream cheese and remaining sugar in large bowl with mixer until blended.