Soften 15g gelatin sheets in ice water for 5–8 minutes, squeeze dry, and stir into 60g warm milk until dissolved. Let cool.
In a clean bowl, beat 280g softened cream cheese with 35g sugar until smooth and creamy.
Add cooled gelatin-milk mixture and stir. Then add 150g heavy cream and mix until silky. Divide mixture into 2 equal parts (~250g each).
For the matcha cheesecake layer: mix 6g matcha powder with 30g warm milk until dissolved. Stir into one portion of cheesecake mixture until evenly green. Pour over chilled Oreo crust, tap pan to release air bubbles, and freeze for 10 minutes until set.
For the Oreo cheesecake layer: fold 15g chopped Oreos into the remaining portion of cheesecake mixture. Gently pour over the matcha layer, tap pan, and refrigerate for at least 4 hours until firm.