Bourbon Butterscotch Ice Cream

Prepare the bourbon butterscotch. Place the butter in a medium heavy-bottomed saucepan over medium heat. Cook until the butter melts, sizzles, and begins to take on a brown, nutty color. When it's richly browned but not burnt, add the cream, brown sugar, bourbon, and salt. Cook the sauce, stirring occasionally to help dissolve the sugar, over medium-high heat until it comes to a boil. Transfer the sauce to a bowl and put it in the refrigerator to cool below 100°F, or body temperature.

Prepare an ice bath. Fill a large bowl two-thirds of the way with very icy ice water and place it in the refrigerator. Boil the milk and glucose. Put the milk and glucose in a medium heavy-bottomed saucepan, and place it over medium high heat. Cook, whisking occasionally to discourage the milk from scorching, until the mixture comes to a full rolling boil, then remove the pot from heat.

Temper the yolks and cook the custard. In a medium bowl, whisk the yolks. Add ½ cup of the hot dairy mixture to the yolks while whisking so the hot milk doesn't scramble the yolks. Pour the tempered yolks back into the pot of hot milk while whisking. Place the pot over medium-low heat and cook, stirring and scraping the bottom of the pot constantly with a rubber spatula to avoid curdling.

Chill. When you notice the custard thickening, or the temperature reaches 180°F on a kitchen thermometer, immediately pour the custard into a shallow metal or glass bowl. Nest the hot bowl into the ice bath, stirring occasionally until it cools down.

Mix the butterscotch into the custard and strain. When the custard is cool to the touch (50°F or below), remove the bowl from the ice bath and add the chilled butterscotch sauce, whisking until evenly combined. Strain it through a fine-mesh sieve to remove any bits of egg yolk. (Straining is optional, but will help ensure the smoothest ice cream possible.)

Cure. Transfer the cooled base to the refrigerator to cure for 4 hours, or preferably overnight. (This step is also optional, but the texture will be much improved with it.)

Churn. Place the custard base into the bowl of an ice cream maker and churn according to the manufacturer's instructions. The ice cream is ready when it thickens into the texture of soft-serve ice cream and holds its shape, typically 20 to 30 minutes.

Harden. To freeze your custard ice cream in the American hard-pack style, immediately transfer it to a container with an airtight lid. Press plastic wrap directly on the surface of the ice cream to prevent ice crystals from forming, cover, and store it in your freezer until it hardens completely, between 4 and 12 hours. Or, feel free to enjoy your ice cream immediately; the texture will be similar to soft-serve.