Combine the milk, sugar, peanut butter, salt and one of the cups of the heavy cream in a pan. Heat up and stir until the sugar is is totally dissolved and the peanut butter is melted. Keep cooking until a bare simmer.

While this peanut butter milk is heating, whisk the egg yolks in a medium bowl. Pour the peanut butter milk into the egg yolks, whisking like crazy. And do this slowly - or you will end up with scrambled eggs. Pour back into the pan and continue cooking, while stirring the entire time, until the mixture thickens (the saying here goes 'until it coats the back of the spoon or spatula). Don't boil it though.

Using a sieve to ensure maximum smoothness, pour the custard into a bowl and sitr in the last cup of heavy cream. Then stir in the vanilla extract. Cover the bowl and refridgerate several hours, but I always refridgerate overnight.

Bust out your ice cream maker and process. When ready pour into a some kind of pan - I used a 9x9 baking pan (as you can see from the picture). What you want is something spread out not tall because...the next step is to drizzle fudge sauce over the ice cream and swirl it through. If you use something narrow and tall you will not successfully swirl the fudge sauce.

And I feel like I am insulting you by saying this, but I don't want any nasty comments about how it didn't work, so...don't heat the fudge hot, using barely warm just a bit pourable fudge sauce. I mean, if it is hot it will undo all the work your ice cream maker just did. No brainer, but just in case...we all have our moments.