Pour the cream into a small saucepan. Set it over low to medium-low heat. You don’t want it to boil aggressively—just warm it until you see steam rising
Once the cream is warm, lower the heat slightly. Add the cocoa powder and powdered sugar gradually, whisking as you go.
At first, it may look a little lumpy or grainy—that’s okay. Keep whisking steadily and the mixture will smooth out.
If you’re using granulated sugar instead of powdered, whisk for an extra minute
Turn off the heat. Add the butter, vanilla extract, and a small pinch of salt to the warm cocoa mixture. Whisk slowly until the butter melts and everything comes together. At this point, you should have a smooth, pourable, glossy ganache
