1 Preheat oven to 190°C (375°F). Grease a 20–23 cm baking dish or pie dish lightly with butter.

2 In a large bowl, toss the raspberries with 75 g granulated sugar, lemon juice, lemon zest, and vanilla extract until evenly coated. Spread the raspberry mixture in the prepared baking dish.

3 In a separate bowl, combine the flour, rolled oats, brown sugar, and salt. Mix with a fork or pastry cutter while adding the cold cubed butter, until the mixture resembles coarse crumbs and some pea-sized pieces remain.

4 Scatter the crumble mixture evenly over the raspberries, pressing lightly so it covers the fruit but still remains crumbly on top.

5 Bake in the preheated oven for 30–35 minutes, or until the crumble topping is golden brown and the fruit is bubbling around the edges.

6 Remove from oven and let cool for 10–15 minutes to set slightly. Serve warm with a scoop of vanilla ice cream if desired.