In a large bowl, combine the milk, chia seeds, pure maple syrup or honey, and peanut butter. Whisk or stir until the peanut butter is mostly incorporated and the mixture is uniform.
Stir in the old fashioned rolled oats until evenly distributed.
Transfer the mixture to one covered container or divide among individual bowls, glasses, or jars, then cover.
Refrigerate overnight (at least 6 hours) until the oats are tender and the mixture is creamy.
Before serving, stir the oats to loosen them. Optionally swirl in a little extra peanut butter and/or drizzle additional maple syrup or honey.