Preheat the oven to 200°C/400°F/gas 6 Tip the frozen berries into a saucepan with half the sugar and place on a medium heat. Squeeze in the juice of half an orange and cook for 5 to 8 minutes, or until the sugar has dissolved and the fruit has softened. Remove from the heat 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 almonds and remaining sugar. Transfer the berry mixture to a 25cm x 30cm 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 vanilla ice cream.