1. Roughly crack the espresso beans in a coffee grinder, or by placing them in a zip-top bag and crushing them with a rolling pin. The goal is to just break the beans up a bit—do not grind them as you would for coffee.
2. Combine the cream, milk, and sugar together in a heavy saucepan over medium heat. Stir until the mixture becomes hot and the sugar dissolves. Remove the saucepan from the heat.
3. Add the cracked espresso beans to the hot milk mixture, cover with a lid, and steep for 30 minutes.
4. Strain the mixture into a large bowl. Check for bits of coffee bean, and strain a second time if required.
5. Return the mixture to the saucepan and reheat over a medium flame.
6. Whisk the egg yolks together in a spacious, heat-tolerant bowl. Temper the yolks by slowly adding one cup of the hot cream mixture while whisking vigorously. Whisk the egg yolks together in a spacious, heat-tolerant bowl. Temper the yolks by slowly adding one cup of the hot cream mixture while whisking vigorously.
7. Reduce the heat to medium-low and whisk the tempered yolks into the saucepan, creating a custard. Stir constantly until the custard thickens slightly and coats the back of a wooden spoon. Immediately strain it into a clean bowl.
NOTE: Stir carefully and do not let the custard boil, or the yolks will curdle.
8. Add the melted chocolate and cocoa to the custard and stir until smooth.
9. Allow the custard to cool to room temperature (approximately one hour). Stir in the vanilla, then refrigerate for 4–6 hours, or overnight.
10. Place the cold custard in the canister of your ice cream maker and process according to the manufacturer’s instructions.
11.Transfer the ice cream to a container, cover, and freeze for at least 4 hours to firm up.
NOTE: For best flavor, always remove ice cream from the freezer 20 minutes before serving, or place it in the microwave for 15–20 seconds.