It’ll take about a half-second glance at the above picture to know whether or not you’re a fifteens person. Anyone who prefers sweet-sweet desserts—and ones with some chew, at that—will forge on; those whose jaws twinge at the first hit of sugar need not proceed. Regardless, if you are from Northern Ireland, this fantastically saccharine (did I mention they’re sweet??) undertaking is a birthright.
What you see is what you get here. Fifteen digestive biscuits, 15 glacé cherries, and 15 marshmallows comprise this quick and easy no-bake “traybake,” regardless of if you’re eating one in or around its birth place of Ulster, Ireland, picking one up at a Belfast Starbucks, or making one right now at (your probably Irish) home.
You may very well be a person who constantly craves snacks that could more accurately be called “confections” and who loves to try new things. Should that be the case, know that the chopped-up marshmallows in this treat provide bounce and lightness, while the crushed-up biscuits allow even just one thin slice of a fifteen to feel significant. A less-than-thorough smashing of said biscuits (and all those chunks of all those cherries) lends texture to the final product, which is otherwise smooth given the pleasant stickiness of the condensed milk.
The ratio is important here. Not only are the matched “fifteens” easy to remember, but when combined with the 3/4 cup condensed milk, the desired texture is achieved. Any more condensed milk and you’d have excessive levels of goop that would demand a clean-up plan post-snacking. Anything more would require tea for softening and dipping (rather than simply benefit from it because it’s a natural and beloved pairing).
Finally, a consistent coating of desiccated coconut around the whole, pre-sliced log is what makes this dessert both craveable and undeniably fun. When portioned post-chilling, each easy-to-grip slice gives sweet, sweet Christmas in July…on any given afternoon. And wherever you are!
Place digestive biscuits in a zip-top bag. Using a rolling pin, pound biscuits until finely crushed (some larger pieces are okay). Transfer to a large bowl. Add cherries and marshmallows. Pour over condensed milk and stir until well combined and the crushed cookies, cherries, and marshmallows are thoroughly coated in condensed milk.
Overlap 2 pieces of plastic wrap on a clean work surface to form an 18- by 15-inch rectangle with the long edge facing you. Sprinkle 1/3 cup of the desiccated coconut in a 12- by 4-inch rectangle in the center of the plastic wrap rectangle. Using a silicone spatula, scrape biscuit mixture on top of the coconut. Using the plastic wrap to squeeze and shape, carefully roll biscuit mixture into a tight 12- by 3-inch log. Sprinkle remaining 1/3 cup desiccated coconut all over the shaped cookie log, pressing to adhere until the log is fully coated. Tightly roll up log with the plastic wrap. Wrap with another layer of plastic wrap, twisting the ends to seal. Chill until firm, at least 4 hours or up to 3 days.
Remove log from refrigerator, and unwrap. Slice log crosswise into 15 slices. Serve.
Make-Ahead and Storage
Fifteens can be made up to 3 days in advance. Keep tightly wrapped, unsliced, and refrigerated.