In a mixing bowl, combine the softened butter and cream cheese using an electric mixer until smooth and creamy.
Gradually add the brown sugar and granulated sugar, mixing until well combined and fluffy.
Sift in the all-purpose flour and salt, mixing on low speed until incorporated.
Add the vanilla extract and mix in milk a little at a time, until you achieve your desired dipping consistency. The dip should be smooth and spreadable, not runny.
Fold in the mini chocolate chips until evenly distributed throughout the mixture.
Transfer the dip to a serving dish and cover with plastic wrap; refrigerate for at least 30 minutes to allow the flavors to meld.
Serve chilled with your choice of dippers, such as graham crackers, pretzels, or fresh fruit.
Notes
Serve the dip in a colorful bowl lined with parchment paper, and arrange an assortment of dippers around the bowl for a beautiful and inviting display.