In a saucepan, whisk together cocoa powder and other 6 Tablespoons of sugar.
Whisk in 1/4 cup of the milk to make a thick paste.
Whisk in remaining milk, cream, and salt.
Heat over medium high heat, and remove when bubbles form around the edges.
Remove from the heat, and whisk in 1/2 cup of the hot cream. Whisk constantly, to avoid cooking the eggs.
Add another 1/2 cup of the hot cream to temper the yolks.
Pour the yolk mixture into the saucepan. Cook over medium heat, stirring constantly until it coats the back of a spoon. You will be able to run your finger down the middle, and it will hold a clear path. Cook for 1 minute longer.
Strain the base to catch any bits. Add vanilla.
Pour into a container and place in an ice bath. Stir occasionally, and when it has cooled, covered with plastic wrap and chill for at least 2 hours or overnight.
Freeze in your ice maker according to the manufacturer instructions. Transfer to a freezer-safe container to freeze until firm.
To take it one step further - make a Sam's Sundae.
Add a few scoops of dark chocolate ice cream to a bowl. Add the olive oil, and sprinkle with salt. Top with freshly whipped cream.