Key lime Dessert

I took this to a family function today and it was a HIT!!  YUMMY!!
1 pouch oatmeal cookie mix
1/2 C. firm butter or margarine
2 cans sweetened condensed milk
3/4 C. key lime juice or lime juice
16 oz. Cool whip, thawed
2 containers yoplait key lime pie yogurt
green food color, if desired
1 tbsp. grated lime peel
fresh berries (blueberries, raspberries, strawberries)

Heat oven to 350.  Spray bottom and sides of a 9x13 pan with cooking spray. 
Place cookie mix in a large bowl, cut in butter with a pastry blender until crumbly and coarse.   Bake 10-12 minutes or until golden brown. cool.
In a large bowl, beat with mixer on medium speed, the sweetened condensed milk and lime juice until smooth and thickened. Remove 1 cup of the cool whip; set aside.  Fold remaining cool whip, yogurt, and food color into the mixture.  Spoon into cooled crust.  Cover and refrigerate about 1 hour or until set. 
Garnish each serving with a dollop of the remaining cool whip, lime peel, and fresh berries.