1 (15 oz.) pkg. Oreo cookies
1/3 c. butter
1/2 gal. ice cream
15 oz. cool Whip
Hershey's chocolate syrup

Crumble package of Oreo cookies; add butter. Pat into bottom of 9x13 inch pan. Save 2/3 cup for top of cake. Add ice cream and Cool Whip. Drizzle syrup over all. Sprinkle crumbs. Refrigerate several hours. Remove 10 minutes before serving.