Prepare the Chocolate Cream Base: In a medium saucepan, combine half of the heavy cream with the Dutch-process cocoa powder. Place over medium heat and gently bring the mixture to a simmer, whisking continuously to fully dissolve the cocoa powder. Once it starts to bubble, remove the pot from heat. Stir in the chopped chocolate until it melts completely, creating a smooth, glossy chocolate mixture. Add the remaining cream and mix thoroughly. Set aside to cool slightly.
Infuse Milk with Chili Flavor: In another medium saucepan, combine the whole milk, granulated sugar, salt, and the halved dried chilies. Heat this mixture over low heat, allowing it to come to a very gentle simmer. The goal is to slowly infuse the milk with the chili’s warmth without boiling.
Temper the Egg Yolks: In a bowl, lightly beat the egg yolks until smooth. Gradually pour a small amount of the warm milk mixture into the yolks—about a quarter cup at a time—while whisking constantly. This step raises the temperature of the yolks slowly to prevent them from curdling. Once the yolks are warmed up, pour the entire yolk mixture back into the milk saucepan.
Cook the Custard: Return the saucepan to medium heat. Stir the mixture constantly with a wooden spoon or heatproof spatula, scraping the sides and bottom frequently to prevent sticking. Cook until the custard thickens enough to coat the back of the spoon—this usually takes about 5 to 7 minutes. Be patient and avoid overheating to prevent scrambling the eggs.
Strain and Combine Custard with Chocolate: Place a fine mesh strainer over the pot containing the chocolate cream base. Slowly pour the custard through the strainer to remove the chili pieces and any cooked egg bits, combining the two mixtures. Stir well until the mixture is evenly smooth and uniformly chocolate in color. Add the vanilla extract and mix again.
Chill the Ice Cream Base: Transfer the chocolate custard to a bowl and cool it down rapidly by placing it in the refrigerator or in an ice bath (a larger bowl filled with ice and cold water). Stir occasionally until completely chilled, about 1 to 2 hours.
Churn and Freeze: Pour the chilled custard into your ice cream maker and follow the manufacturer’s instructions to churn until the mixture reaches a soft-serve consistency. Transfer the ice cream to an airtight container and freeze for at least 3 to 4 hours, or overnight, for a firmer texture.
No Ice Cream Maker Alternative: If you don’t have an ice cream maker, pour the chilled custard into a shallow container and place it in the freezer. Every 30 minutes, remove the container and vigorously stir or blend the mixture to break up ice crystals. Repeat this process for about 4 hours, then let it freeze fully for several more hours before serving.