Peel, core and quarter the apples, then cut into chunks.
Place the apples in a pan with the sugar and cook over a low heat, stirring occasionally, for 10 minutes, or until slightly softened. Remove from the heat, stir through the frozen berries and leave to cool a little.
Meanwhile, cube the butter and place in a mixing bowl with the flour. Rub together with your fingertips until it resembles breadcrumbs, then stir in the Granola Dust.
Transfer the fruit mixture to a baking dish and sprinkle over the crumble topping.
Bake in the oven for 25 to 30 minutes, or until golden and crunchy. Delicious served with a dollop of yoghurt.