Spray 8x8 or 9x9 pan with non-stick spray. Line pan with parchment paper allowing for overhang. Spray parchment paper with non-stick spray, set aside.
In medium sauce pan combine sugar, corn syrup and water.
Cook over medium high heat until mixture has liquefied.
Keep stirring for about 10 minutes until mixture has turned a deep amber color.
Remove pan from heat and stir in condensed milk and butter (mixture will bubble) Whisk until smooth.
Return mixture to medium low heat and mix continuously until thermometer reads 240°. If you do not have a candy thermometer, keep a glass of ice water nearby. Drop a glob of the mixture in water, if it forms a sticky ball shape, the caramel is hot enough.
Remove mixture from heat, whisk in kosher salt and Bourbon, pour into prepared pan.
Cool in refrigerator for a few hours until set.
Sprinkle with sea salt flakes and slice in ¾ inch squares and wrap with wax paper squares.
Can be stored in airtight container at room temperature for 2 weeks.