I have just made this and it is fantastic
10 1/2 oz cooking apples, peeled cored and diced
6fl oz hot water
3 1/2 oz caster sugar
5 1/2 oz blackberries
Put chopped apples, water and sugar in a pan and simmer until apples are pureed. (about 5 mins) transfer to a blender add the blackberries and blitz. Pass through a sieve (i am going to try putting it in the passata machine next time). Freeze in a ice cream machine or pour into a freezer proof container and put in freezer, after 2 hours remove and stir with a fork to break down the ice crystals, return to freezer and repeat after another 2 hours, then leave to freeze. Remove from freezer 5 mins before use, allowing it to soften slightly.