Mix the Dry Ingredients. In a mixing bowl, combine the old-fashioned oats, unsweetened cocoa powder, and chia seeds. Stir until these dry ingredients are evenly mixed.
Add the Wet Ingredients. Pour in your choice of milk, creamy peanut butter, and honey. Mix everything thoroughly until you have a smooth, chocolatey mixture.
Divide into Containers. Distribute the chocolate oat mixture evenly into individual airtight containers or mason jars, depending on how many servings you're preparing.
Refrigerate Overnight. Seal the containers and place them in the refrigerator. Allow the oats to soak and develop their flavors overnight or for at least 4-6 hours.
Serve and Enjoy. When you're ready to enjoy your Chocolate Overnight Oats with Peanut Butter, simply remove them from the refrigerator. Give them a good stir, and if desired, top with sliced bananas, strawberries, a drizzle of honey, or additional peanut butter.