Cappuccino-Toffee Crunch Ice Cream

Pour 2 cups of the half-and-half into a heavy saucepan. Bring to a simmer over medium-high heat. Add the cocoa and espresso powder and whisk to blend. Add the cinnamon stick and remove from the heat.

In a heatproof bowl, whisk together the egg yolks and all of the sugar until blended. Form a kitchen towel into a ring and place the bowl on top to prevent it from moving.

Gradually pour the hot half-and-half mixture into the yolk mixture, whisking constantly. Return the mixture to the same saucepan and place over medium-low heat. Cook, stirring slowly and continuously with a wooden spatula, until the custard thickens and leaves a path on the back of the spatula when a finger is drawn across it, about 5 minutes; do not allow the custard to boil.

Pour the custard through a medium-mesh sieve set over a clean heatproof bowl. Add the chocolate and stir until melted. Stir in the Kahlúa, rum and the remaining 1/4 cup half-and-half. Refrigerate the custard until cold, about 1 hour.

Transfer the custard to an ice cream maker and freeze according to the manufacturer's instructions. Add the nut crunch during the final minute of freezing. Transfer the ice cream to a freezer-safe container. Cover and freeze until firm, at least 4 hours or up to 3 days, before serving.