Combine cherries, granulated sugar, cornstarch, lemon juice, and vanilla in a large bowl until evenly coated

Transfer the cherry mixture into the baking dish, spreading it out evenly

In another bowl, mix oats, flour, brown sugar, cinnamon, and salt until combined

Pour in melted butter and stir until the mixture forms crumbly clusters

Sprinkle the crumble topping evenly over the cherries, covering most of the surface

Place the dish in the oven and bake until the topping is golden and the filling is bubbling around the edges

Remove from the oven and let it cool slightly so the juices thicken before serving