Line the loaf pan with parchment paper, leaving extra on the sides to lift the cake later. The pan should be fully covered on the bottom and sides.
Pour the cold heavy cream into a bowl. Add sugar and whip until the cream is fluffy and holds soft peaks. It should look smooth and spreadable, not stiff.
Spread a thin layer of whipped cream on the bottom of the pan. This helps the cookies stay in place.
Place a single layer of Biscoff cookies over the cream. Fit them close together so there are no big gaps.
Spread more whipped cream over the cookies. The cookies should be fully covered.
Repeat the cookie and cream layers until the pan is full. Finish with a cream layer on top.
Cover the pan and place it in the fridge overnight. The cookies will soften and the cake will firm up.
When the cake is set, gently warm the cookie butter just until spreadable. Spread it evenly over the top.
Sprinkle crushed Biscoff cookies on top. Add whole cookies if you want.
Lift the cake out using the parchment. Slice into thick pieces and serve cold.