Berry crumble

Preheat your oven to 180°C (350°F).
In a large mixing bowl, combine the mixed berries, granulated sugar, cornstarch, lemon juice, and lemon zest. Toss them together until the berries are evenly coated with the sugar and cornstarch mixture. Transfer the berry mixture into a baking dish (approximately 20cm x 20cm or similar size).
In another mixing bowl, prepare the crumble topping. Combine the all-purpose flour, rolled oats, brown sugar, salt, and ground cinnamon (if using). Mix well.
Add the cold, cubed butter to the dry crumble mixture. Use your fingertips or a pastry cutter to work the butter into the dry ingredients until the mixture resembles coarse crumbs and the butter is well incorporated.
Sprinkle the crumble topping evenly over the berry mixture in the baking dish.
Place the baking dish in the preheated oven and bake for about 30 minutes, or until the topping is golden brown, and the berry filling is bubbling.
Remove the berry crumble from the oven and allow it to cool slightly before serving.
Serve your berry crumble warm, ideally with a scoop of vanilla ice cream or a dollop of whipped cream if desired.
Enjoy your homemade berry crumble with its delightful combination of sweet, juicy berries and crispy crumble topping!