Preheat your oven to 350°F. Start by preparing a 9x9-inch baking pan. Line the pan with aluminum foil for easier cleanup and spray it with cooking spray; this will help the bars come out seamlessly.
In a medium saucepan, combine the butterscotch chips and butter. Heat over medium to medium-low heat, stirring continuously until melted. It may take about 5 minutes for the chips to melt completely, and the mixture will look unappealing at first, so keep whisking!
Once the mixture is smooth and emulsified, remove it from the heat. Add the graham cracker crumbs and stir until well combined. Set aside one heaping cup of this mixture to top the bars later.
Transfer the remaining mixture into the prepared pan, using a spatula to hard-pack it evenly into a smooth crust. Set this aside as you prepare the filling.
In a large mixing bowl (or stand mixer), add the cream cheese and beat on high for 2 to 3 minutes until smooth and fluffy. Don't forget to scrape down the sides of the bowl to ensure everything is mixed well.
Add in the egg, sweetened condensed milk, vanilla, and salt. Beat the mixture again until everything is fully incorporated. It’s normal to see small blobs of cream cheese; just keep mixing until they’re diminished.
Pour the cheesecake filling evenly over the prepared crust, ensuring it’s well spread out.
Sprinkle the reserved butterscotch crumb mixture evenly on top of the filling, which will create a delightful texture contrast.
Bake in the preheated oven for about 32 to 35 minutes, or until the top is set but still slightly jiggly. Start checking around 25 to 30 minutes, as oven times can vary.
Once done, allow the bars to cool in the pan for about 1 hour at room temperature. Then cover and refrigerate until well chilled before slicing into squares and serving.
