Finely grind tuille biscuits.

Melt unsalted butter.

Grate orange zest.

Combine ground biscuits, melted butter, and orange zest.

Pack the mixture firmly into an 8-inch springform pan.

Chill the crust.

Press cottage cheese through a fine-mesh strainer into a bowl.

Add yogurt, mascarpone, lemon juice, and caster sugar to the strained cottage cheese.

Bloom gelatine sheets according to package instructions.

Combine heavy cream and bloomed gelatin.

Heat gently until the gelatin melts completely.

Fold the cream and gelatin mixture into the cottage cheese mixture.

Transfer the cheesecake mixture to the prepared pan.

Chill for 2-3 hours, or overnight, until firm.

Loosen the edges of the cheesecake from the pan.

Remove the cheesecake from the springform pan.

Decorate with red grapefruit slices.

Crumble reserved biscuit mixture.

Sprinkle the crumbled biscuit over the top of the cheesecake.