Preheat oven to 375°F.
In a mixing bowl, gently combine the berries with the cane sugar, lemon juice, flour, cinnamon, and ginger. Spoon into a shallow baking dish.
In a separate bowl, combine the butter with the rolled oats, flour, hazelnuts, sugar, cinnamon, cardamom, and sea salt. Cut the butter into the mixture in small piece, and work it into the dry mixture with your fingers until the topping is coarse and chunky.
Spread the crumble topping loosely over the berry mixture.
Bake until the berry mix is bubbling at the edges and golden, 30-35 minutes. Allow to cool for at least 15 minutes before serving.