"Happy campers of all ages will love Frozen S'mores. (Ice cream stands in for the marshmallows used in the original campfire treat.) Take time to freeze this dessert after spreading the chocolate sauce on the first and second layers of graham crackers. If you don't, you'll lose those sharp, clean lines. The recipe calls for vanilla and chocolate ice cream, but try any flavor that complements the graham crackers and chocolate."
Microwave cream and chocolate in a 1-quart glass measuring cup on high power until very hot, about 2 minutes. Whisk until chocolate melts into a smooth sauce.
Line an 8-inch square metal pan with plastic wrap, leaving an overhang. Arrange 1/3 of the graham crackers over bottom, cutting the final few with a knife to fit. Drizzle 1/3 of the sauce over the crackers; spread evenly. Freeze until chocolate is just set, 5 to 10 minutes.
Spread vanilla ice cream over the chocolate. Top with another cracker layer as before. Drizzle another 1/3 of the sauce over the crackers; spread evenly. Freeze until just set, 5 to 10 minutes. Spread chocolate ice cream over the crackers. Arrange a final layer of crackers over the ice cream. Spread remaining sauce over crackers.
Freeze until set, about 2 hours, or double-wrap in plastic and freeze up to 5 days.
To serve, lift dessert from pan; discard plastic wrap. Halve the dessert; cut each half into 6 slices. Return to freezer briefly. Toast marshmallows over a flame and serve alongside s'mores.