In a bowl, add icing sugar, cocoa powder, and hot water. Mix until smooth.
Add melted dark chocolate. Mix again until glossy and lump-free.
Add condensed milk, cream, vanilla, and pinch of salt. Mix until completely smooth and silky.
In a separate bowl, using a paddle attachment, beat the butter for about 5 minutes until creamy, smooth, and lighter in texture.
Slowly add the chocolate mixture into the butter while beating on low-medium speed.
Beat until ultra smooth, glossy, silky, creamy, and shiny like gelato.
Scrape the bowl once or twice while mixing for the smoothest finish.
