In a medium saucepan, over no heat, combine the milk (1½ cups), 1 cup of the cream, and the sugar.
1½ cups whole milk, 1½ cups heavy cream, ⅔ cup sugar
In a large bowl, whisk together the egg yolks and the remaining ½ cup of cream until blended. Add the cocoa powder and whisk until fully mixed and no lumps are visible.
4 large egg yolks, 3 tablespoon unsweetened cocoa powder
Place the saucepan over medium heat and cook, stirring often, until bubbles form around the edges of the pan and the sugar dissolves, about 4 to 5 minutes. Do not allow it to boil. Remove from heat.
Slowly pour about ¾ of the warm cream mixture into the bowl with the egg yolks, whisking constantly. Now, slowly pour the yolk mixture into the saucepan with the remaining warm cream, still whisking. Place the saucepan back over medium heat and cook, stirring constantly, until the custard is thick enough to coat the back of the spoon, about 4 to 5 minutes. Do not boil.
Remove the saucepan from the heat. Add the chocolate to the custard and let it rest for 1 to 2 minutes. Then, gently stir until the chocolate is melted and the custard is smooth. Stir in the vanilla until blended.
6 oz semisweet chocolate, 2 teaspoon vanilla extract
Pour the warm custard through a sieve into a clean bowl, gently pressing the liquid through the sieve, leaving any grainy solids in the sieve.
Place the bowl of custard in an ice bath in a large bowl for 30 to 45 minutes. Place a piece of plastic wrap directly onto the surface of the custard and over the sides of the bowl. Refrigerate for at least 3 hours, or preferably overnight.
Prepare your ice cream maker with at least a 1-quart capacity according to the manufacturer's directions. Pour the custard into the ice cream maker and churn until the custard reaches the consistency of thick cream.
Transfer to a plastic freezer container with a lid and freeze until frim, at least 3 hours, or preferably overnight.
Video
Notes
NOTE: Watch the video near the top of the recipe for visual guidance.This recipe makes 1 quart. Double the recipe for larger ice cream machines, if desired.The ice cream will initially be very soft before you freeze it. Once frozen, it will be solid. To make scooping easier, let the ice cream tub sit out on the counter for 15 to 20 minutes. The ice cream will keep in the freezer for a couple of weeks.