Dump a lot of heavy cream into a bowl, and whip it until it holds a medium-to-stiff peak. If you're measuring, I like to whip 3 cups of cream for each sleeve of cookies. Before whipping, you can fold in flavorings; sometimes, I add a splash of vanilla or a big pinch of confectioner's sugar, but the cream is great as is.
Take a cookie, spread a spoonful of whipped cream on top of it, and top it with another cookie. Repeat until you have a little tower. When the tower gets too high, lay it on its side.
Build another tower of cookies, lay it on its side, and connect your two cookie-logs. Repeat until the sleeve of wafers is finished, reserving some of your whipped cream. You should have one, big, messy log of cookies and cream.
Frost the log with your remaining whipped cream.
Cover your cake with foil, and let it rest in the fridge overnight. Before serving, you can garnish it with chocolate shavings or sprinkles -- but I usually just slice it on the bias and dig in.