Beat the heavy cream with the vanilla and sugar until stiff peaks form.
Arrange ice cream sandwiches on the bottom of a 9'''' x 5'''' loaf pan. I use 2 full ones and 2 with about 1/4 cut off of them. Top this with 1/3 of the whipped cream and sprinkle with 1/3 of the chopped candy bar. If using, drizzle with chocolate sauce.
Repeat 2 more times, using the remaining ice cream sandwiches, whipped cream and candy bar.
Freeze at least one hour or until very hard. (If leaving longer than 1 hour wrap in plastic wrap.)
To serve, allow cake to thaw on the counter for about 5 minutes. Remove from loaf pan and slice.