Soak the gelatine in 100 ml milk for 10 minutes. Heat the rest of the milk, vanilla and honey in a small saucepan and let it simmer. Add the milk with the soaked gelatine and stir well. Remove the saucepan from the heat and fold in the Greek yogurt. Now pour the mixture into glasses and let it cool down in the refrigerator for at least 3 hours, but better overnight.
Heat the blueberries with honey in a saucepan. Mash the blueberries a little with a fork so that some juice comes out. Let the blueberries simmer gently for about 2 minutes while stirring. Mix the cornstarch with the water and stir into the berry and honey mixture. Reduce a little more until the juice has thickened.