Toss together the blackberries and golden caster sugar in a large bowl. Leave for 30 mins or until the fruit starts to break down, then mash the berries a little with a fork.
In a separate bowl, mix the Greek yogurt with the honey and goat’s milk. Spoon the yogurt mixture into a freezable container, then tip the berries on top and swirl them through. Freeze for 2 hrs, then give a little stir and return to the freezer to firm up. Take out of the freezer a few mins before serving to soften for scooping.