Bring soy milk and milk to the boil in a heavy-based saucepan, stirring occasionally with a whisk. Add confectioners' sugar and green tea powder, whisking briskly so no lumps form. Stir gelatin into milk mixture and remove saucepan from heat.
Place the bottom of the pan in a bowl of ice-cold water; set aside until mixture starts to thicken. Add cream and gently stir. Pour the mixture through a sieve and then evenly pour into 6 small serving cups. Chill in the refrigerator for 1 hour.
