Warm the milk, sugar, salt and ½ cup of the cream in a medium saucepan. With a sharp paring knife, scrape the flavorful seeds from the vanilla bean and add them, along with the pod, to the hot milk mixture. Cover, remove from the heat, and let steep at room temperature for 30 minutes.
Rewarm the vanilla-infused mixture. Pour the remaining 1 cup cream into a large bowl and set a mesh strainer on top. In a separate medium bowl, whisk together the egg yolks. Slowly pour the warm mixture into the egg yolks, whisking constantly, then scrape the warmed egg yolks back into the saucepan.
Stir the mixture constantly over medium heat with a heatproof spatula, scraping the bottom as you stir, until the mixture thickens and coats the spatula. Pour the custard through the strainer and stir it into the cream to cool. Remove the vanilla bean, wipe it clean of any egg bits, and add it back to the custard. Stir in the vanilla and stir until cool over an ice bath. Chill thoroughly in the refrigerator.
When ready to churn the ice cream, remove the vanilla bean (it can be rinsed and reused). Freeze the ice cream in your ice cream maker according to the manufacturer's instructions. While the ice cream is freezing, chop the peanuts into bite-sized peanuts.
Fold the peanut pieces into the frozen ice cream as you remove it from the machine, and layer it with Fudge Ripple.
To make the Chocolate-Covered Peanuts
Put the pieces of chocolate in an absolutely dry heatproof bowl. Set the bowl over a saucepan of simmering water to melt the chocolate, stirring until smooth. In the meantime, stretch a piece of plastic wrap over a dinner plate.
Once the chocolate is melted, remove it from the heat and stir in the peanuts, coating them with the chocolate. Spread the mixture on the plastic-lined plate and chill.
Mixing them in
Use a chef's knife to chop the chocolate-covered block of peanuts into bite-sized pieces, then mix them into 1 quart of ice cream as you remove it from the machine.
Chocolate-Covered Peanuts can be stored for several months in an air-tight container, refrigerated at room temperature.
To make the Fudge Ripple
Whisk together the sugar, corn syrup, water, and cocoa powder in a medium saucepan. Heat over medium heat, whisking constantly, until the mixture begins to bubble at the edges.
Continue to whisk until it just comes to a low boil. Cook for 1 minute, whisking frequently. Remove from the heat, stir in the vanilla, and let cool. Chill in the refrigerator before using.
Mixing it in
The Fudge Ripple should be thoroughly chilled, as it's easiest to use when very cold. Just before you remove the ice cream from the machine, spoon some of the Fudge Ripple onto the bottom of the storage container. As you remove the ice cream from the machine, layer generous spoonfuls of the sauce between layers of ice cream. Avoid stirring the Fudge Ripple, as it will make the ice cream muddy looking.
Fudge Ripple can be stored for up to 2 weeks, covered, in the refrigerator.