In a large bowl, add the brownie mix and combine with the eggs, oil, and water. Mix well with a hand mixer until mixed well.
Line a muffin pan with paper cups and add about 1 large tablespoon of batter to the paper cups. Add a handful of peanut butter chips on top of the brownie batter in the cups. Top off the rest of the batter, smoothing out the tops to cover the chips well.