Melt the butter in a skillet over medium heat. Add the diced apple, chopped dates, cinnamon, cardamom, and a tiny pinch of salt.
Cook for about 8–10 minutes, stirring occasionally, until the apples become tender and lightly caramelized.
Transfer the warm apple mixture to a mixing bowl. Add the rolled oats, chia seeds, milk, Greek yogurt, vanilla protein powder, and the remaining cinnamon and cardamom.
Stir everything together until the ingredients are evenly distributed and the mixture becomes creamy.
Cover and refrigerate for at least 3 hours, preferably overnight, allowing the oats and chia seeds to absorb the liquid.
Give the oats a good stir before serving. Add extra diced apple, cinnamon, chopped nuts, or a small drizzle of nut butter if desired.
