Place the chocolate chips in a microwave safe bowl and melt in the microwave in 15 second intervals stirring each time until smooth. Set aside.
In the bowl of an electric mixer, mix together the butter and sugar on medium speed until light and fluffy. Turn the mixer to low and add the eggs one at a time incorporating thoroughly after each addition. Add the mascarpone and sour cream to the bowl and mix to combine.
In a medium bowl, whisk together the confectioners sugar, cocoa powder and salt. Add half the dry ingredients to the wet ingredients and mix on low speed until thoroughly combined. Add the melted chocolate and continue mixing to combine. Add the remaining dry ingredients and mix until all the dough is smooth and creamy.
Using a rubber spatula, gently fold in the chocolate chunks. Transfer the dip to a serving bowl and serve with cookies, crackers, fruit or my favorite, Pretzel Crisps!
Note: Dip can be stored in the refrigerator in an airtight container for up to 24 hours. Alternatively, the dip can be frozen in an airtight container for up to 30 days.