Melt the chocolate in a heat-proof bowl set over a pot with an inch of simmering water. Or alternately, carefully melt in microwave on half power checking every 30 seconds. Cool until just barely warm. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment or with a hand mixer, beat the cream cheese and butter on medium-high speed until its fluffy and light. This should take about 3 to 4 minutes. Slowly beat in the confectionery sugar, cocoa powder and salt. Add the melted, cooled chocolate and beat until combined. Add the sour cream and beat until the mixture fully mixed and well blended.