Mix rolled oats, cinnamon, chia seeds, and salt in a bowl or jar until evenly combined for a balanced flavor base.
Add milk, Greek yogurt, vanilla, and maple syrup, then stir until the mixture becomes smooth and creamy.
Fold in optional apple or extra seeds to adjust texture and natural sweetness before chilling.
Transfer into sealed containers and let rest briefly so the oats begin absorbing liquid evenly.
Refrigerate overnight for at least 6–8 hours until fully softened and creamy.
Stir well before serving and add toppings like fruit, nuts, or extra cinnamon.