Grease a 2-litre pudding bowl with the butter, then put 300g of the summer fruit mix into the bottom of the bowl and set aside.
In a separate large bowl, whisk together the vanilla sponge mix with the ground almonds, the eggs and the yogurt.
Whizz the remaining fruit mix in a blender for a few seconds until you have a smooth purée, then fold it into the sponge mixture. Pour the sponge mixture into the pudding bowl to cover the fruit.
Cover the bowl with cling film and microwave on full power for 8–10 minutes. Once cooked, immediately remove the cling film, being careful of the hot steam that will escape. Turn out onto a serving plate and let the juices run down the sides. Serve with an extra dollop of yogurt for a yummy treat.