I didn't make the praline candies to mix in just because I got impatient, but I'm sure they'd take this perfect ice cream to perfecto mundo levels.
Salted Butter Caramel Ice Cream
from David Lebovitz
One generous quart
For the caramel praline (mix-in)
½ cup sugar
¾ teaspoon sea salt, such as fleur de sel
For the ice cream custard
2 cups whole milk, divided
1½ cups sugar
4 tablespoons salted butter
scant ½ teaspoon sea salt
1 cup heavy cream
5 large egg yolks
¾ teaspoon vanilla extract
1. To make the caramel praline, spread the ½ cup of sugar in an even layer in a medium-sized, unlined heavy duty saucepan: I use a 6 quart/liter pan. Line a baking sheet with a silicone baking mat or brush it sparingly with unflavored oil.
2. 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.
3. Without hesitation, sprinkle in the ¾ teaspoon salt without stirring (don't even pause to scratch your nose), then pour the caramel onto the prepared baking sheet and lift up the baking sheet immediately, tilting and swirling it almost vertically to encourage the caramel to form as thin a layer as possible. Set aside to harden and cool.
4. To make the ice cream, 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 of the milk into the inner bowl, and rest a mesh strainer on top of it.
5. Spread 1½ cups sugar in the saucepan in an even layer. Cook over moderate heat, until caramelized, using the same method described in Step #2.
6. 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 of the milk.
7. 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.
8. 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.
9. Freeze the mixture in your ice cream maker according to the manufacturer's instructions.
10. While the ice cream is churning, crumble the hardened caramel praline into very little bits, about the size of very large confetti (about ½-inch, or 1 cm). I use a mortar and pestle, although you can make your own kind of music using your hands or a rolling pin.
11. Once your caramel ice cream is churned, quickly stir in the crushed caramel, then chill in the freezer until firm.
Note: As the ice cream sits, the little bits of caramel may liquefy and get runny and gooey, which is what they're intended to do.