In a large mixing bowl, combine 600 ml of double cream, 397 g of condensed milk, and 275 g of Biscoff spread. Whisk until smooth, about 1-2 minutes.

Crush 125 g of Biscoff biscuits into small chunks and set aside. Optionally, melt 125 g of Biscoff spread in the microwave for 20-30 seconds until pourable.

Layer one-third of the ice cream mixture in a container, drizzle one-third of the melted Biscoff spread, then sprinkle one-third of the crushed biscuits. Repeat twice.

Cover the container tightly and freeze for at least 4 hours or until solid.