In a jar or container, combine oats, chia seeds, protein powder, milk, Greek yoghurt, sweetener (if using), espresso, and cacao. Stir well.
½ cup rolled oats, 2 tbsp chia seeds, 1 scoop protein powder, 3/4 cup milk, ⅓ cup Greek yoghurt, 2 tbsp espresso shot, 1 teaspoon cacao nibs