Prepare the Frappe BaseIn a blender, combine the milk, ice, Biscoff cookie spread, 1 or 2 Biscoff cookies (broken into pieces), vanilla extract, and brown sugar (if using). Blend on high speed until the mixture is smooth and frothy, with the ice fully crushed and the cookies blended into the drink.
Serve the FrappePour the Biscoff frappe into a tall glass, leaving some room at the top for whipped cream.
Top and GarnishTop the frappe with a generous swirl of whipped cream. Drizzle extra Biscoff cookie spread over the whipped cream for a rich, caramelized topping. For extra crunch and decoration, sprinkle crushed Biscoff cookie crumbs on top.
Enjoy!Serve immediately with a straw or spoon, and enjoy the delicious, creamy Biscoff Frappe!