Combine the chocolate, cocoa powder, and salt in a medium bowl.
Combine the glucose, sugar, and heavy cream in a heavy-bottomed saucepan and stir intermittently while bringing to a boil over high heat. The moment it boils, pour it into the bowl holding the chocolate. Let sit for 1 full minute.
Slowly, slowly begin to whisk the mixture. Then continue, increasing the vigor of your whisking every 30 seconds, until the mixture is glossy and silky-smooth. This will take 2 to 4 minutes, depending on your speed and strength.
You can use the sauce at this point or store it in an airtight container in the fridge for up to 2 weeks; do not freeze.
