PREHEAT oven to 350° F. Grease a 9-inch springform pan.
PLACE whole bar of dough onto bottom of prepared pan. Allow to soften for 5 to 10 minutes. Using fingertips, pat dough gently to cover bottom.
BAKE for 18 to 19 minutes or until light golden brown. Cool completely in pan on wire rack.
SPREAD ice cream over top of cookie. Spread whipped topping over ice cream. Freeze for at least 2 hours.
THAW for 5 to 10 minutes; remove side of springform pan. Top with hot fudge sauce and nuts before serving.