Add the heavy cream, whole milk, cocoa powder, and sugar to a large sauce pan. Heat the mixture over medium until it just starts to bubble.
Add in the semi sweet chocolate and stir until it is totally melted and can be stirred smooth.
Add the egg yolks to a medium sized bowl and whisk them together until smooth.
Slowly pour 1/2 cup of the chocolate cream mixture into the egg yolks, and whisk them together until combined.
Add another 1/2 cup of the chocolate cream, then another until it's all combined.
Pour the egg mixture back into the sauce pan and continue to let it cook over medium for another couple minutes until the mixture starts to thicken.
Stir in the salt and vanilla extract.
Pour the mixture though a fine mesh strainer, into a large bowl.
Put the bowl over another large bowl full of ice. Let the ice cream mixture chill over the ice for about 10 minutes, stirring occasionally.
Cover the bowl and place it in the fridge for 30 minutes to 1 hour.
Pour the mixture into a prepared ice cream maker, allow to run according to the ice cream makers manufactures instructions (about 25 to 30 minutes), or until thick.
Scoop 1/3 of the ice cream into a 2 quart pan (a 9x5 loaf pan works great). Sprinkle about 1/3 of the marshmallows, nuts, and chocolate over the chocolate ice
Repeat with additional ice cream, toppings, ice cream and toppings until it's all in the pan.
Cover and transfer the ice cream to the freezer for another 6 hours minimum, up to overnight to get the ice cream to freeze solid.