In a medium saucepan, melt the butter. Stir in the sugar and cocoa. Gradually stir in the cream. Heat over medium heat, stirring constantly, until the mixture is smooth and hot but not boiling. Remove from the heat and stir in vanilla and salt. Use warm as a sauce or glaze, or let it cool and spread like frosting. Store leftover sauce covered in the fridge. Reheat gently in pan of simmering water, or in a microwave on low.
NOTE: To crumb coat a cake before glazing, let the sauce cool to a soft frosting consistency. Spread a very thin layer of it over the cake to glue to the crumbs and provide a smooth surface for the glaze. Refrigerate the cake for just 5 or 10 minutes to set the surface.
To glaze the cake, reheat the remaining sauce gently, stirring until it is smooth, glossy, and pourable. Pour over the cake.
My career was sparked by a single bite of a chocolate truffle, made by my Paris landlady in 1972. I returned home to open this country’s first chocolate bakery and dessert shop, Cocolat, and I am often “blamed” for introducing chocolate truffles to America. Today I am the James Beard Foundation and IACP award-winning author of ten cookbooks, teach a chocolate dessert class on Craftsy.com, and work with some of the world’s best chocolate companies. In 2018, I won the IACP Award for Best Food-Focused Column (this one!).