Place milks, custard powder, sugar and vanilla bean paste in a bowl, whisking to combine. Transfer mixture to a saucepan and cook, stirring constantly, over medium heat for 5 minutes or until thickened.
Remove pan from heat and allow custard to cool slightly. Add half the yoghurt, stirring to combine.
Divide three quarters of the blueberries among six serving glasses. Pour over half the custard, sprinkle over remaining berries, then top with remaining custard. Chill glasses in fridge for at least 1 hour or until custard is set.
When ready to serve, remove from fridge and serve topped with remaining yoghurt.