Add the granulated sugar, 2 tablespoons light brown sugar, lemon juice, cornstarch, vanilla extract and 1/4 teaspoon kosher salt. Toss gently until the fruit is evenly coated and the cornstarch is distributed. Let sit for 10 minutes to macerate; juices will thicken slightly.

Transfer the fruit and any accumulated juices into the prepared baking dish and spread into an even layer.

Brown sugar oat crumble topping

While the fruit macerates, make the crumble: in a medium bowl combine the rolled oats, all-purpose flour, 2/3 cup light brown sugar, 1/4 cup dark brown sugar (if using), ground cinnamon and 1/4 teaspoon sea salt. Stir to combine.

Add the cold cubed butter to the dry mixture. Using a pastry cutter, two forks or your fingertips, cut the butter into the mixture until it resembles coarse crumbs with some pea-sized pieces. The cold butter creates a mix of crisp and tender textures when baked.

Stir in the toasted chopped pecans or walnuts, if using.

Evenly sprinkle the oat crumble over the fruit in the baking dish, covering the fruit completely. Drizzle the 1 tablespoon melted butter over the top and, if desired, lightly sprinkle the turbinado sugar for added crunch.

Place the cobbler on a baking sheet (to catch any bubbling juices) and bake in the preheated oven for 35–40 minutes, or until the topping is golden brown and the fruit filling is bubbling around the edges. If the topping browns too quickly, tent loosely with foil for the last 10 minutes.

Remove from the oven and allow the cobbler to rest for 10–15 minutes; the filling will thicken as it cools slightly.

Finishing & serving

Scoop warm cobbler into bowls and top each portion with a scoop of vanilla ice cream.

Drizzle about 2 tablespoons (≈30 ml) of caramel sauce over each serving (adjust to taste).

Serve immediately while the cobbler is warm and the ice cream begins to melt into the crumble. Leftover cobbler can be refrigerated for up to 3 days and gently reheated in a 350°F (175°C) oven until warm.