Instructions:
- Combine the butter in a medium, heavy-bottomed saucepan over medium heat and melt until just foamy.
- Whisk in the granulated sugar and cocoa powder. Cook, stirring constantly, for 1 minute until the mixture is smooth and fragrant (blooming the cocoa).
- Slowly whisk in the water until the mixture is completely uniform. Bring this mixture to a gentle simmer, stirring often, and cook for 2 minutes.
- Slowly pour in the heavy cream while whisking continuously. Bring the mixture back to a gentle simmer.
- Remove the pan from the heat immediately. Add the chocolate chips and the flaky sea salt. Let stand undisturbed for 2 minutes to allow the chocolate to soften.
- Whisk gently, starting from the centre and working your way out, until the sauce is completely smooth, glossy, and fully emulsified.
- Stir in the vanilla extract.
- Transfer the sauce to a storage jar. The sauce will thicken significantly as it cools. Serve warm or at room temperature over your favourite dessert.