In small saucepan, place 120ml whipping cream, extra dark chocolate, and dark chocolate.
Heat over medium-low heat until chocolate melts, stirring frequently.
Remove from heat; set aside.
In a medium saucepan over medium heat, heat half-and-half until very hot but not boiling, stirring often.
Remove from heat, set aside.
In a small bowl, combine sugar and cocoa powder. Set aside.
Attach bowl and wire whip to mixer.
Place egg yolks in the mixer bowl. Turn mixer to speed 2 and gradually add sugar mixture; mix about 30 seconds or until well blended and slightly thickened.
Continuing on Speed 2, very gradually add chocolate mixture and half-and-half, mix until well blended.
Return the combined chocolate and half-and-half mixture to medium saucepan, stirring constantly, cook over medium heat until small bubbles form around edge and mixture is steamy.
DO NOT BOIL.
Transfer half and half mixture into a large bowl; stir in remaining 330ml (1 1/2 cups) whipping cream, vanilla and salt.
Cover and chill thoroughly in the fridge for at least 8 hours.
If using the KitchenAid Ice Cream Attachment – Assemble and engage freeze bowl, dasher and drive assembly following the instructions in the attachment manual.
Turn to STIR Speed (Speed 1)
Using a container with a spout, pour the mixture into the freeze bowl.
Continue on STIR (Speed 1) for 19 to 15 minutes or until desired consistency, adding milk chocolate during last 1 to 2 minutes of freeze time.
Immediately transfer ice cream into serving dishes, or freeze in an airtight container.
