Melt the butter in a large pan over medium-low heat.

Add the apples and sugar. Cook for about 5 minutes or until the apples are softened.

Add in the blueberries and cook for another 2-3 minutes. Stirring occasionally. Transfer the fruit to an oven proof dish.

Next to make the topping. Using your fingers rub the butter and flour together until it resembles fine breadcrumbs. Add the sugar and cinnamon. Mix everything together well.

Add in the yogurt and milk and mix together to form a thick paste.

Using a tablespoon drop the mixture spoon by spoon onto the fruit. Don't worry about gaps as it will fill out and rise during baking.

Sprinkle the oats and then sugar over the dough.