In a large microwave-safe bowl, add the dry brownie mix. Microwave in 30-second increments, stirring after each, for a total of 2 minutes. Set aside to cool.
In a separate large bowl, use an electric mixer to beat the softened cream cheese on medium speed until smooth and creamy.
Add the prepared brownie mix and milk to the cream cheese. Beat until well combined and smooth.
Gently fold in the thawed whipped topping until completely blended into the mixture.
Fold in the mini chocolate chips until evenly distributed throughout the dip.
Transfer the dip to a serving bowl and sprinkle additional mini chocolate chips on top, if desired. Serve immediately with your favorite dippers such as pretzels, graham crackers, cookies, or fruit.