Directions

1. Heat oven to 350°F. Spray bottom and sides of 8- or 9-inch square pan with cooking spray.
2. In large bowl, place cookie mix. With pastry blender or fork, cut in butter until mixture is crumbly and coarse. Reserve 1 1/2 cups crumb mixture; press remaining crumbs in bottom of pan. Bake 10 minutes.
3. In small bowl, stir together sugar and cornstarch. Gently stir in yogurt. Spoon yogurt mixture evenly over crust. Sprinkle blackberries evenly over yogurt. Top with reserved crumb mixture.
4. Bake 43 to 47 minutes or until light golden brown. Cool 30 minutes. Refrigerate about 2 hours or until thoroughly chilled. For bars, cut into 4 rows by 4 rows. Store covered in refrigerator.