In a mixing bowl, combine the rolled oats, cocoa powder, and a pinch of salt. Mix well to distribute the cocoa evenly.
Add the milk, honey (or maple syrup), vanilla extract, and Greek yogurt to the oats mixture. Stir thoroughly until all ingredients are combined and the oats are well coated.
Divide the mixture into two airtight containers or jars. Make sure to leave some space at the top as the oats will expand while soaking.
Cover the containers or jars with their lids and refrigerate overnight (or for at least 4 hours) to allow the oats to soften and absorb the flavors.
In the morning, give the overnight oats a good stir. If they seem too thick, you can add a splash of milk to reach your desired consistency.
Top with your choice of sliced bananas, berries, nuts, or shredded coconut before serving.
Consider experimenting with different sweeteners or toppings based on your taste preferences.
For a protein boost, consider adding a scoop of protein powder to the mix.