- Special equipment:A candy thermometer
Lightly coat an 8x8" baking pan with nonstick spray and line with parchment paper, leaving a 2" overhang on 2 sides; spray parchment.
Bring sugar, corn syrup, and 1/2 cup water to a boil in a medium saucepan over medium-high heat, stirring to dissolve sugar. Cook, swirling pan occasionally, until mixture turns a deep amber color, 8–10 minutes.
Remove pan from heat and whisk in sweetened condensed milk and butter (mixture will bubble vigorously) until smooth. Fit pan with thermometer and return to medium-low heat. Cook, whisking constantly, until thermometer registers 240°F. Remove from heat and whisk in bourbon and kosher salt. Pour into prepared pan; let cool. Sprinkle caramel with sea salt, cut into 3/4" pieces, and wrap individually in parchment paper.
DO AHEAD: Caramels can be made 2 weeks ahead. Store wrapped tightly in plastic in airtight container at room temperature.