Combine the milk, flax seeds, and peanut butter powder. In a liquid measuring cup measure the milk. Add the flax seeds and peanut butter powder. Stir well.
Combine oats and peanut butter. In a small mason jar with a lid (or another container with a lid), add the peanut butter then the oats. Pour the milk mixture on top. If you'd like the swirl the peanut butter throughout, use the butter knife to do so otherwise leave as is. Cover.
Let Sit. Refrigerate overnight (or at least 3 hours).
Garnish. To serve, add fresh fruit such as sliced bananas and blueberries if desired.
This overnight oatmeal is pretty thick. For thinner oatmeal, add more milk when making the oatmeal or in the morning. Topping Ideas: