Makes one generous quart (liter)
2 cups [500 ml] whole milk, divided
1½ cups [300 g] sugar
4 tbsp [60 g] salted butter
½ tsp [2.5 ml] sea salt (see note)
1 cup [250 ml] heavy cream
5 large egg yolks
¾ tsp [3.75 ml] vanilla extract
Make an ice bath by filling a large bowl about a third full with ice cubes and adding a cup or so of water so they’re floating. Nest a smaller metal bowl (at least 2 quarts/liters) over the ice, pour 1 cup (250 ml) of the milk into the inner bowl, and rest a mesh strainer on top of it.
Spread 1½ cups [300 g] sugar in the saucepan in an even layer. Heat the sugar over moderate heat until the edges begin to melt. Use a heatproof utensil to gently stir the liquefied sugar from the bottom and edges towards the center, stirring, until all the sugar is dissolved. (Or most of it—there may be some lumps, which will melt later.) Continue to cook stirring infrequently until the caramel starts smoking and begins to smell like it’s just about to burn. It won’t take long.
Once caramelized, remove from heat and stir in the butter and salt, until butter is melted, then gradually whisk in the cream, stirring as you go. The caramel may harden and seize, but return it to the heat and continue to stir over low heat until any hard caramel is melted. Stir in 1 cup (250 ml) of the milk.
Whisk the yolks in a small bowl and gradually pour some of the warm caramel mixture over the yolks, stirring constantly. Scrape the warmed yolks back into the saucepan and cook the custard using a heatproof utensil, stirring constantly (scraping the bottom as you stir) until the mixture thickens. If using an instant-read thermometer, it should read 160°-170°F (71°-77°C). Pour the custard through the strainer into the milk set over the ice bath, add the vanilla, then stir frequently until the mixture is cooled down. Refrigerate at least 8 hours or until thoroughly chilled.
Freeze the mixture in your ice cream maker according to the manufacturer’s instructions.
Notes: Be sure to use good salt (fleur de sel, Maldon, fine gray salt or kosher salt). Don’t use ordinary fine table salt; it’s far too harsh. Because of the caramel in this ice cream, once churned and frozen, it’ll remain nice & creamy (as shown in the photo.) To make it firmer, crank up your freezer a bit or store it in a shallow pan.
Recipe Credit: Adapted from David LebovitzYum