In a large bowl, whisk together the flour, salt, brown sugar, granulated sugar, oats, cinnamon, and grated nutmeg.
Add the cold, cubed butter and use your hands or a pastry blender to work the butter into the flour and sugar mixture to form coarse crumbs.
Add the crushed cinnamon candy to the crumb mixture and stir to combine.
Spread the topping evenly over the apples in the baking dish.
Place the casserole dish onto a baking sheet and place into the preheated oven.
Bake for 60 minutes, or until the topping is golden and the apple juices start to bubble around the edges of the dish.
Remove and allow to cool slightly.
Serve warm or at room temperature with ice cream or whipped cream, if desired.