Over medium heat, add the half and half to a medium saucepan and heat until hot, but not boiling. Stir often. Remove from heat and set aside.
Place egg yolks and sugar in the mixer bowl of a stand mixer. Mix on low with a wire whip for about 30 seconds or until slightly thickened. Gradually add half and half and mix until blended. Return the mixture to the saucepan and cook over medium heat until mixture is steaming, but not boiling. Stir constantly. Transfer to a large bowl and stir in the whipping cream, vanilla and salt. Cover and chill for at least 8 hours or overnight.
Freeze in an ice cream maker according to manufacturer's directions. Add the chopped hazelnuts in the last 5 minutes of churning.
Layer ⅓ of the ice cream mixture into the bottom of a chilled freezer safe container. Drizzle with ⅓ of the salted caramel in large ribbons and use a knife to gently cut into the ice cream. Repeat 2 times, ending with more large ribbons of caramel. Sprinkle with additional hazelnuts if desired. Cover with plastic wrap or foil and freeze for at least 2 hours or up to 3 days.