In a bowl, whisk together chia seeds, almond milk, maple syrup, vanilla, and half of the cinnamon.
Let the mixture sit for 10 minutes, then stir again to prevent clumping. Cover and refrigerate at least 2 hours or overnight.
In a skillet, warm coconut oil over medium heat. Add diced apples, remaining cinnamon, and a pinch of salt. Cook until apples soften and become fragrant.
Stir oats and nuts into the skillet, letting them toast lightly with the apples.
To serve, spoon chia pudding into glasses or bowls, then top generously with the warm apple crumble mixture.