Begin by crushing the Lotus Biscoff biscuits in a food processor until they resemble fine crumbs. Melt the unsalted butter and mix it with the biscuit crumbs and a pinch of salt until combined.

Press the mixture into the bottom of an 8-inch square baking pan to create a compact base.

In a heavy-based saucepan, melt the unsalted butter over medium heat. Add light brown sugar and sweetened condensed milk, stirring constantly until thick and golden.

Remove from heat and stir in Lotus Biscoff spread and a pinch of salt until smooth.

Pour the caramel over the biscuit base and spread it evenly. Cover and chill in the refrigerator for at least 2 hours.

Melt the chopped milk chocolate in a microwave-safe bowl in 30-second intervals until smooth. Pour over the chilled caramel and spread evenly.

Chill for an additional hour, then cut into squares for serving.