Beat softened cream cheese and butter in a bowl until smooth and fluffy.
Add powdered sugar, brown sugar, and cocoa; mix on low, then increase speed until combined.
Pour in vanilla and half the milk. Beat until creamy. Add more milk to reach dip consistency.
Mix in salt and the espresso powder if using.
Fold in mini chocolate chips.
Chill 10 minutes for best texture, then serve with dippers.