1. Heat oven to 325Â°F. Grease or spray bottom only of 13x9-inch pan.
2. In large bowl, beat cake mix and butter with electric mixer on low speed until crumbly; reserve 1 cup. Press remaining crumbly mixture, using floured fingers, in bottom of pan.
3. In same bowl, beat cream cheese, yogurt and frosting on medium speed until smooth. Beat in eggs until blended. Pour into pan. Sprinkle with reserved crumbly mixture.
4. Bake 40 to 45 minutes or until center is set. Cool 30 minutes. Refrigerate at least 2 hours until chilled. Just before serving, stir strawberries and blueberries into pie filling. Top each serving with berry mixture. Store covered in refrigerator.
Heat oven to 350Â°F. At end of step 2, prebake crust about 10 minutes.