Step 1

Prepare the Bourbon Ice Cream Base: Cook whipping cream, milk, brown sugar, and salt in a medium saucepan over medium, stirring occasionally, until sugar is dissolved and mixture is steaming, about 5 minutes. Remove from heat. Whisk egg yolks in a small bowl until pale, about 1 minute. Slowly pour or ladle 1 cup hot cream mixture into yolks, whisking constantly. Whisk warm yolk mixture back into remaining cream mixture in saucepan.

Step 2

Cook mixture over low, stirring constantly, until thickened and a thermometer registers 175°F, about 5 to 7 minutes. Remove from heat, and stir in bourbon and vanilla bean paste. Pour mixture through a fine mesh strainer into a large bowl, discarding solids. Cover surface of cream mixture with plastic wrap, pressing plastic wrap directly on surface, and refrigerate until completely chilled, at least 4 hours or up to overnight (12 hours).

Step 3

Prepare the Bourbon-Caramel Swirl: Cook granulated sugar and 2 tablespoons water in a medium saucepan over medium, swirling occasionally (but do not stir), until sugar has dissolved and caramel reaches a golden amber color, about 10 minutes. Remove from heat, and carefully whisk in warmed whipping cream. Whisk in bourbon and salt. Set aside to cool to room temperature, about 30 minutes.

Step 4

Meanwhile, pour chilled Bourbon Ice Cream Base into the bowl of an electric ice-cream maker, and freeze according to manufacturer's instructions. When Bourbon Ice Cream Base reaches a soft-serve consistency, spoon about 1 cup ice cream into a 9-x 5-inch metal loaf pan. Drizzle about 2 tablespoons cooled Bourbon-Caramel Swirl over ice cream. Repeat ice cream and caramel layers 3 more times; reserve any leftover Bourbon-Caramel Swirl for serving or another use, and store in an airtight container or jar in refrigerator for up to 2 weeks. Smooth top, and cover with plastic wrap or parchment paper, pressing plastic wrap or parchment directly onto surface. Freeze until firm, at least 4 hours.