Prepare an 8x8 inch pan by lining with parchment paper. Create flaps that hang over edges for easy removal. Set aside.
In a medium microwave-safe bowl, heat semi-sweet chocolate chips in 30 second intervals until melted and smooth. Careful not to scorch.
Pour about half of melted chocolate into prepared pan and smooth evenly with a silicone or offset spatula. Place in freezer to harden, about 15 minutes.
Meanwhile, place marshmallows and butter in a microwave-safe bowl and heat on high for about 45 seconds. Stir and return to microwave for about another 45 seconds. Add whiskey to melted marshmallows & stir until smooth and elastic.
Working quickly, pour the melted marshmallows onto set chocolate layer and, smooth as evenly as possible. A silicone spatula is the best tool for this job.
Return to freezer and freeze for another 15 minutes.
Place unwrapped caramels into a bowl. (I used the same bowl I melted the marshmallows in to minimize the mess.) Heat for about 45 seconds, then stir, and continue heating in 30 second intervals until melted and smooth.
Quickly pour over marshmallow layer and spread as evenly as possible. (It will begin to harden, so move fast.) Return to freezer for 15 more minutes.
Pour remaining melted chocolate over caramel layer. Smooth evenly and, while still wet, sprinkle with crumbled bacon.
Freeze for a final 15-30 minutes or until completely set.
When ready to cut, remove bark by gently pulling on parchment flaps, then carefully peel from parchment. Cut into pieces with a sharp knife.
Keep refrigerated as the bark softens and interior becomes gooey at room temperature.