01 - Line a baking sheet with parchment paper. Arrange 8 Biscoff biscuits flat side up, evenly spaced apart.
02 - In a medium mixing bowl, add the slightly softened vanilla ice cream. Dollop the Biscoff spread on top and gently swirl with a spoon until a marbled pattern forms. Avoid overmixing to maintain distinct ribbons of Biscoff throughout.
03 - Spoon equal portions of the Biscoff-swirled ice cream onto each of the 8 arranged biscuits, spreading it into an even layer about ¾ inch thick.
04 - Place the remaining 8 biscuits on top of the ice cream, flat side down. Gently press each sandwich together until the ice cream reaches the edges.
05 - If desired, dip one half of each sandwich into melted chocolate, allowing excess to drip off. Immediately sprinkle with crushed Biscoff cookies before the chocolate sets.
06 - Place all assembled sandwiches on the lined baking sheet and transfer to the freezer. Freeze for at least 2 hours, or until the ice cream is completely firm.
07 - Remove from the freezer and serve immediately. Let stand for 2 to 3 minutes at room temperature if the sandwiches are too firm to bite into comfortably.