Prepare the chia seed jam: Add the berries, chia seeds, maple syrup, and water to a small saucepan. Cook over low heat, using the back of a fork to gently mash the berries, until the mixture thickens to a jam-like consistency.
Prepare the oats: In a large glass container, combine the oats, cinnamon, and milk. Mix well, cover, and refrigerate overnight.
Prepare the yogurt mixture: In a separate glass container, combine the PB2, yogurt, and ¼ cup of milk. Mix well and refrigerate until ready to assemble.
Assemble: When ready to serve, add a layer of the overnight oats to a mason jar, followed by a layer of chia seed jam. Top with the yogurt mixture, then finish with peanuts, peanut butter, and fresh berries.