• In a medium saucepan, whisk 1 1/4 cup (310 ml) of the milk with the cream, sugar, cornstarch, and cocoa powder. Set over medium heat and bring to a boil while whisking constantly. When it boils, lower the heat to the minimum and simmer for about 5 to 6 minutes, until the mixture is thick and creamy.
• Remove from the heat, add the chopped chocolate, then stir until the chocolate is completely melted. Mix in the coffee liqueur, if using, and finally, whisk in the remaining milk. Let cool to room temperature, then refrigerate at least 2 hours, or preferably overnight.
• Strain the dark chocolate gelato custard through a fine-mesh strainer (straining the mixture will ensure a silky smooth gelato). Pour into the bowl of an ice cream maker. Freeze according to the manufacturer’s instructions. Stop the machine when the gelato is icy but still soft.
• STORAGE: Transfer the gelato to an airtight container and freeze until firm, about two hours. The gelato will keep, frozen, for up to 1 month.
• SERVING: Always take the gelato out to room temperature 10 to 15 minutes before serving to soften it, make it easier to scoop, and return it to its optimal texture.
• NOTE—VEGAN OPTION: For the best flavor and texture, combine oat milk with coconut cream. Oat milk has a smooth, subtle flavor that is very close to that of dairy milk, whereas coconut cream delivers an unbelievably rich texture. Coconut milk and coconut cream both have quite a strong flavor, so using only coconut cream and combining it with oat milk creates the perfect balance.

Having said that, here's how to substitute the original ingredients to make this vegan chocolate gelato:

• Replace the full quantity of cow's milk (2 1/4 cups / 560 ml) with oat milk
• Replace the full quantity of heavy cream (3/4 cup / 180 ml) with coconut cream
• Be aware that the terms "coconut milk" and "coconut cream" are sometimes used interchangeably. To make sure you're buying real coconut cream, choose a product with at least 20% fat content. The label of quality coconut cream products will always clearly indicate the fat content.
• If you don't mind an underlying coconut flavor (it marries really well with the taste of dark chocolate!), you can use a combination of coconut milk and cream. Alternatively, you can use other plant-based milks and cream, keeping the same milk-to-cream ratio for the best texture. Always make sure the vegan products you choose can withstand being heated and boiled to avoid the chocolate gelato turning grainy. Products labeled with the word "Barista" are sure picks: it means they can withstand high heat.