Frozen Lemonade Squares

I just finished putting this dessert together for dinner tonight. I am posting the recipe in anticipation of its yumminess. That's right, I've never had it before but its just sounds scrumdilicious!

Frozen Lemonade Squares
Ingredients:
9 graham crackers - finely crushed (about 1 1/4 cups)
1/4 cup (1/2 stick) softened butter
1 qt (4 cups) vanilla low-fat yogurt
6 oz. frozen lemonade concentrate --- I went ahead & used the entire can!
1/2 cup cool whip

Make it:
Mix graham cracker crumbs and butter, press onto bottom of 9-inch square pan - I used a bigger rectangular pan.
Beat yogurt and concentrate with mixer until well blended; spread over crust.
Freeze for 4 hours or until firm.
Serve topped with cool whip