In a mason jar, combine oats, milk, and Greek yogurt
Add cocoa powder, peanut butter, honey, vanilla extract, and salt
Stir mixture thoroughly until cocoa powder is fully incorporated
Add chia seeds and stir again
Seal container and refrigerate overnight (minimum 6 hours)
In the morning, stir well to combine all ingredients
Add a splash of milk if mixture is too thick
Top with optional garnishes just before serving