01 - In a large mixing bowl, whip the cold heavy cream using an electric mixer on medium-high speed until stiff peaks form, approximately 2 to 3 minutes.
02 - Gently fold the sweetened condensed milk, vanilla extract, and melted Biscoff spread into the whipped cream using a spatula. Work in smooth, sweeping motions to maintain the airy texture until fully combined.
03 - Transfer the mixture into a loaf pan lined with parchment paper. Smooth the surface evenly, then cover tightly and freeze for at least 4 hours or until completely firm.
04 - Remove the ice cream from the freezer and let it rest at room temperature for about 5 minutes to soften slightly for easier scooping.
05 - Arrange 8 Biscoff cookies flat side up on a baking sheet. Scoop approximately 1/4 cup of ice cream onto each cookie, then top with a second cookie. Gently press down to form an even sandwich.
06 - If desired, roll the exposed edges of each sandwich in crushed Biscoff cookies to coat. Place the assembled sandwiches back on the baking sheet.
07 - Return the sandwiches to the freezer for 10 to 15 minutes to firm up before serving.