In a medium saucepan, bring the cream, corn syrup, sugar, and cocoa powder to a boil over medium to medium-high heat.
Add the chocolate and simmer over medium heat until the chocolate melts, stirring occasionally with a wooden spoon.
Take the pan off the heat and stir in the olive oil, vanilla, and salt. The olive oil may separate at first, but with gentle stirring (or whisking) it will all come together.
Use immediately or let cool to room temp and refrigerate, covered, for up to three months.
Gently reheat the sauce in the microwave, in a microwave safe container, in 30 second intervals, stirring between each one. Or reheat on the stove top: place the sauce in a heat proof bowl and place the bowl over a pot of simmering water, over medium heat. Stir until warmed. The olive oil may separate when u reheat the sauce – don’t be alarmed: when you stir it will come back together.