Preheat the oven to 350°F and line a 9 x 9-inch square baking pan with parchment paper on all sides. Set aside.
Brown the butter over medium heat, stirring constantly until the butter begins to foam and turns a golden brown, emitting a nutty aroma. As soon as the butter starts to turn brown and smell nutty, take it off the heat to prevent any more liquid from escaping. Take the butter off the heat and set aside to cool slightly.
In a large mixing bowl combine the brown sugar, all-purpose flour, oats, baking soda, and salt. Stir to combine. Make a well in the center and add the browned butter, egg yolk and vanilla extract. Stir until the mixture starts to come together to form a dough. It will be a little dry, almost like a shortbread!
Add the chocolate chips and mix to distribute. Transfer about half the dough into your prepared pan, patting it into an even layer. Set aside while you make the caramel layer.
Place the unwrapped caramels and heavy cream in a medium sauce pan over low-medium heat. Using a rubber spatula, stir to the caramels constantly until completely melted, about 3 minutes. Once melted, remove from the heat immediately. Stir in the salt and vanilla extract.
Pour the caramel over the bottom layer in your pan. Press the remaining dough over the top of the caramel, gently patting it into an even layer. Don’t worry if it doesn’t cover the caramel completely—a little caramel peeking through is totally fine!
Bake for 30 minutes or until the bars are golden brown all over and you can the caramel starting to bubble slightly. Let the bars cool completely before slicing and serving!