1. Begin by melting 80g of butter in a pot over a gentle steam bath. Ensure the butter dissolves completely to form a liquid consistency.

2. Grind the Oreo cookies into a powder and place it into an 8-inch mold with a removable bottom.

3. Combine the liquid butter with the cookie powder, mixing thoroughly.

4. Press the mixture firmly into the mold using a tool, then refrigerate for about 30 minutes to set the crust.

5. In a separate container, mix 350g of yogurt with approximately 40g of powdered sugar until well combined. Opt for a thicker yogurt variety for best results.

6. Stir the yogurt mixture until smooth and set aside.

7. In another container, combine 15g of gelatin powder with around 70g of milk. Allow the mixture to stand for about five minutes to thicken.

8. After the gelatin mixture has thickened, heat it gently over a steam bath until any particles dissolve. Let it cool slightly.

9. Pour 300g of heavy cream into a bowl and whip until it reaches about 70% of its volume. For smoother whipping, you can chill the cream and add around 10g of powdered sugar before whipping.

10. Mix the whipped cream and the yogurt until the mixture thickens to a desirable consistency.

11. Add the prepared custard mixture to the yogurt-cream blend, stirring until thoroughly combined.

12. Incorporate 15g of matcha tea powder into the mixture, ensuring it's evenly distributed for a vibrant green hue.

13. Retrieve the Oreo crust from the refrigerator and transfer the mousse mixture onto it.

14. Carefully place the mold in the refrigerator to chill for at least 6 hours. This allows the mousse to set beautifully.

15. Once chilled, gently warm the mold's edges with a hairdryer to aid in easy unmolding. Sprinkle a touch of matcha powder on top for a finishing touch.

16. For an extra flair, consider decorating the top with fresh fruits.