Ingredients
1/2 cup sugar
1/4 cup unsweetened cocoa powder
3/4 cup heavy cream
1/4 cup plus 2 tablespoons light corn syrup
3 ounces semisweet chocolate, chopped
2 tablespoons unsalted butter
1 teaspoon vanilla extract
Pinch of salt
Preparation
Combine the sugar and cocoa powder in the top of a double boiler set over briskly simmering water, and whisk to combine. Add the heavy cream and corn syrup, and whisk until smooth. Cook, whisking constantly, until the mixture is hot, thick, and creamy, 3 to 5 minutes. Add the chocolate, butter, vanilla, and salt, and stir to combine. Cook, stirring occasionally, until the chocolate and butter are melted and the sauce is smooth, 2 to 3 minutes. Keep warm until ready to serve. Store it in a nonreactive airtight container, refrigerated.
