Preheat your oven to 375°F (190°C) and lightly grease a 9×9 inch baking dish or a similar-sized pie plate.

In a large mixing bowl, toss the prepared strawberries with the granulated sugar, cornstarch, lemon juice, and vanilla extract until the berries are evenly coated.

Pour the strawberry mixture into your prepared baking dish and spread them out into an even layer.

In a separate medium bowl, combine the flour, rolled oats, brown sugar, cinnamon, and salt. Add the cold, cubed butter to the dry ingredients.

Use a pastry cutter, a fork, or your fingers to work the butter into the mixture until it resembles coarse crumbs and no large chunks of butter remain.

Sprinkle the crumble topping evenly over the strawberries, covering them completely.

Place the dish in the oven and bake for 35 to 40 minutes, or until the fruit filling is bubbling around the edges and the topping is golden brown and crisp.

Remove the crumble from the oven and let it cool for at least 10 to 15 minutes before serving. This allows the fruit juices to thicken slightly.

Serve warm, ideally with a scoop of vanilla ice cream or a dollop of whipped cream.