Preheat oven to 350 degrees F. Line an 8×8-inch square baking pan with parchment paper.
Make the Shortbread: In a mixing bowl, beat together the butter and sugar with an electric mixer on medium speed until light and fluffy, 2 to 3 minutes.
Add vanilla and salt and beat until combined. Add flour and mix until incorporated; dough may appear slightly crumbly.
Firmly press into prepared pan. Poke shallow holes into the surface of the dough with a fork or skewer.
Bake 18 to 22 minutes, or until the edges are lightly golden. Remove pan from oven and set on a wire rack.
Make the Caramel Layer: Place the caramel candies in a small saucepan over medium heat. Add the heavy cream and stir until completely melted. Pour hot caramel mixture over shortbread crust and spread into an even layer. Refrigerate until set, 30 minutes to 1 hour.
Make the Cookie Dough: Combine the butter and sugars in a large mixing bowl and beat on medium speed until light and fluffy, 2 to 3 minutes. Add the heavy cream and vanilla; mix well. Add the flour and salt and mix on low speed until incorporated. Stir in the chocolate chips. Spread the cookie dough on top of the caramel layer, using a spatula to smooth the dough into an even layer. Refrigerate the pan while you prepare the glaze.
Make the Chocolate Glaze: In a small bowl, combine the chocolate and butter and microwave on 50% power in 30-second increments, stirring after each, until completely melted and smooth. Spread the glaze over the cookie dough layer and chill until set, about 30 minutes.
To remove the bars from the pan, grasp the edges of the parchment paper and lift out the entire block. Place on a cutting board and use a large sharp knife to cut into 2-inch squares. Stored in an airtight container, bars will keep for up to 3 days.