In a large mixing bowl, whisk together the first 5 ingredients (reserving a few cookies for garnish) until smooth and well blended.
Fold in bananas and cookies.
Pour into a large serving bowl, top with small container of cool whip and garnish with reserved cookies.
Cover and chill until ready to serve.
Notes
I like to make this the day before and let it chill in the refrigerator overnight. The flavors taste much better and the cookies soften and become cake-like.