Preheat oven to 350

Line 9X13 metal baking pan with parchment

For the crust: In the bowl of a stand mixer, or using a hand mixer and large bowl, mix the softened butter and powdered sugar until combined.  Add the flour and mix until crumbly and well incorporated.  Press the dough evenly into the baking pan and bake for 18-20 minutes until the shortbread is set and lightly golden brown.

For the caramel: Melt the butter in a medium saucepan over medium low heat.  Once the butter has melted add the brown sugar and corn syrup , raise the temperature to medium high, and whisk to combine.  Heat the sugar mixture until small bubbles form at the edge of the pan then add the sweetened condensed milk.  Continue to cook over medium high and bring the caramel to a boil.  Boil for 5 minutes whisking constantly.  After 5 minutes, remove from heat and stir in the vanilla and salt.  Continue to stir off the heat for an additional 2-3 minutes.  Pour the warm caramel over the shortbread and allow to set.

For the Peanut Butter: Mix the melted butter with the peanut butter until well combined.  Add in the powdered sugar and mix until well incorporated and smooth.  Gently pour the peanut butter mix over the set caramel.  Place the bars in the refrigerator for 20-30 minutes to set before adding the chocolate layer.

For the Chocolate: Once the peanut butter layer has set, melt the chocolate chips with 2 teaspoons of oil.  I melt chocolate in the microwave beginning with 30 seconds, then 15 second intervals, stirring between each heat cycle*. Pour the warm chocolate over the bars and spread to cover.  Allow the chocolate to set before slicing into bars.