1. Place the chocolate in a heatproof bowl or the top of a double boiler; set over a pan of simmering water. Heat, stirring with a rubber spatula, until melted and smooth.

2. Place 1/2 cup plus 1 1/2 teaspoons water in a small pan; bring to a boil. Remove from heat.

3. Add the cocoa powder to the boiling water, and whisk until smooth. Add the melted chocolate, heavy cream, melted butter, confectioners sugar, brandy, and corn syrup; whisk mixture to combine.

4. Return pan to medium-high heat. Cook, whisking constantly, until bubbly and thick, about 2 minutes. Use while still warm.