Preheat the oven to 190°C (375°F).
In a large mixing bowl, toss the sliced apples with granulated sugar, cinnamon, and lemon juice until evenly coated.
Transfer the apple mixture into a 23cm (9-inch) square baking dish, spreading it into an even layer.
In a separate bowl, combine the flour, rolled oats, light brown sugar, and salt.
Incorporate the chilled vegan butter cubes into the dry mixture using a pastry cutter or fingertips until the texture resembles coarse breadcrumbs.
Distribute the crumble topping evenly over the apple filling layer.
Bake for 35 to 45 minutes, or until the topping is golden brown and the filling juices are bubbling.
Remove from the oven and allow to set for 10 minutes before serving.