adapted slightly from David Lebovitz
2 cups whole milk, divided
1 1/2 cups sugar
4 tablespoons salted butter
1/2 teaspoon flaked sea salt
1 1/2 cups heavy cream
5 egg yolks
3/4 teaspoon vanilla
Fill a large bowl 1/3 of the way with ice and then place a smaller bowl inside it. Pour 1 cup of the milk into the bowl. Set aside. In a large stainless steel saucepan spread the sugar in an even layer. Over a medium heat, wait until the sugar begins to melt around the edges. Using a silicon spatula or other heat-safe utensil, slowly scrape the saucepan towards the center until all the sugar has dissolved. Continue to cook, stirring occasionally, until the sugar just starts to smoke. Remove from heat and immediately add in the salt and butter and whisk until all the butter is melted. Slowly stir in the cream, whisking as you pour.
Return the saucepan to the burner, turning it down to a low heat. Stir in 1 cup of milk. In a small bowl beat the five egg yolks. Temper the yolks by placing a ladle-full of caramel liquid into the beaten yolks, whisking as you pour. Then pour the yolks into the caramel and continue cooking until the caramel mixture is thick and the temperature reaches 160° F. Remove from heat.
Using a wire mesh strainer, strain the caramel liquid into the milk in the ice bath. Whisk together and stir until mixture is warm and not hot. Place the mixture in the fridge until it is cold, at least 5 hours, and then churn in your ice cream maker according to the manufacturer’s directions. After churning, stir in any desired extras, like 1 cup chopped chocolate-covered pretzels, and then freeze.
Makes 6 cups ice cream.