Begin by crushing the caramel biscuits into fine crumbs using a food processor or a rolling pin. In a mixing bowl, combine the biscuit crumbs with melted unsalted butter until well-coated. Press this mixture firmly into the bottom of a lined 8-inch springform pan to create a solid base. Chill in the refrigerator for about 10 minutes to set.

In a large bowl, beat the softened cream cheese with 10 g of caster sugar until smooth and creamy, ensuring there are no lumps. In a separate bowl, dissolve the soaked gelatin in 80 ml of hot milk, then mix in the Earl Grey tea powder. Gradually fold this tea mixture into the cream cheese until fully blended.

In another bowl, whip the heavy cream until it achieves soft peaks. Gently fold the whipped cream into the cheese-tea mixture, being careful to maintain the airy texture. Finally, add about two tablespoons of crushed biscuit pieces for added flavor and texture.

Pour the creamy mousse mixture over the chilled biscuit base, spreading it evenly with a spatula. Smooth the top and gently shake the pan from side to side to remove any air bubbles. Cover the pan with plastic wrap and refrigerate for a minimum of 4 hours, or until set.

If you choose to make the mirror glaze, start by steeping an Earl Grey tea bag in 100 ml of hot milk. Dissolve 5 g of caster sugar and gelatin sheets in this liquid while stirring. Allow the glaze mixture to cool slightly before carefully pouring it over the set mousse layer.

Return the cheesecake to the fridge for another 1 to 2 hours to allow the mirror glaze to firm up. Once set, carefully unmold the cheesecake using a hairdryer to gently warm the edges of the pan for easy release. Decorate with additional crushed caramel biscuits.