Make the crumb base: Crush the Biscoff biscuits into fine crumbs. Stir in melted butter, brown sugar, and salt until the mixture looks like wet sand.
Pack the base: Spoon crumbs into each cup and press down firmly with the back of a spoon.
Aim for an even, compact layer.
Whip the cream: In a cold bowl, whip the heavy cream to medium peaks. Do not overwhip.
Beat the cream cheese: In another bowl, beat cream cheese, powdered sugar, and vanilla until smooth. Mix in 100 g Biscoff spread and lemon juice if using.
Fold together: Gently fold the whipped cream into the cream cheese mixture in two additions until creamy and uniform.
Fill the cups: Pipe or spoon the cheesecake mixture over the crumb base, leaving room for topping.
Smooth the surface.
Chill: Cover and refrigerate for at least 2–3 hours, or until set. Overnight gives the best texture.
Add the topping: Warm the remaining Biscoff spread until just pourable (microwave 10–15 seconds). Pour a thin layer over each cup.
Tilt gently to spread.
Finish and serve: Chill 15–20 more minutes to set the topping. Garnish with crushed biscuits and a pinch of flaky salt if you like.