Preheat your oven to 350°F (175°C) and grease a 9x9-inch baking dish with butter or line it with parchment paper.

Combine all-purpose flour, rolled oats, brown sugar, and cold butter in a large mixing bowl. Mix until it resembles coarse crumbs, about 5-7 minutes.

Press half of the crumble mixture firmly into the bottom of the baking dish and bake for 15-20 minutes until lightly golden.

Peel, core, and slice the apples. Sauté them in a skillet with sugar and cinnamon over medium heat for 5-8 minutes until slightly softened.

Spread the sautéed apples over the baked crust and crumble the remaining mixture over the apples.

Bake for an additional 25-30 minutes or until the top is golden brown and bubbly.

Let the bars cool for 10-15 minutes, then drizzle generously with salted caramel sauce.

Once cooled, slice into squares and serve, optionally with vanilla ice cream.