Prepare one 9" cake round according to package directions. Allow to cool and then place in the freezer until ready to use.
Butter a 9" Spring form pan. Then spread 1/2 of the ice cream into the pan. Place spoonfuls of the hot fudge sauce on top of the ice cream. Then sprinkle the cookies on top. Swirl the top with a knife. Then tap on the counter to smooth out the top. Then spread the rest of the ice cream on top. Place in the freezer for at least 4 hours, or until firm.
Place the prepared (and cooled) 9" cake round onto a cake plate. When the ice cream is firm, release from the spring form on top of the cake round. Then immediately spread with the whipped cream.
Place back in the freezer for 30 minutes. Then decorate as desired. Serve immediately.
Tip: Run your knife under hot water and then dry it before cutting for a smooth cut. Short on time for baking? You can buy pre-made cake rounds from your local bakery at most grocery stores.