Reprinted with permission from The Ciao Bella Book of Gelato and Sorbetto
3 Cups Water
1 1/2 Cups Granulated Sugar
4 Ounces Bittersweet Chocolate (About 60% Cacao), Finely Chopped
1/2 Cup Unsweetened Cocoa Powder
1 Teaspoon Dark Rum
1/4 Teaspoon Vanilla Extract
In a medium saucepan, combine the water and sugar. Place over medium-high heat and bring to a boil, whisking often to dissolve the sugar. Reduce the heat to medium-low and simmer for 4 minutes, continuing to whisk until all the sugar is dissolved.
Remove the pan from the heat and add the chopped chocolate; whisk until the chocolate is completely melted. Add the cocoa powder and whisk until incorporated and the mixture is smooth. Add the rum and vanilla, then pour though a fine-mesh strainer into a clean bowl. Let cool, stirring often. Once cooled, cover and refrigerate until very cold, at least 4 hours or overnight.
Churn in your ice cream maker according to the manufacturer's instructions. Transfer to an airtight container and freeze for at least 2 hours before serving.