Using an electric mixer on medium speed, beat the butter and sugar until light and fluffy. Add the vanilla and salt, beating until combined. Add the flour and mix until combined. (Dough may be crumbly.)

Press the dough into the bottom of the prepared pan. Using a fork, poke shallow holes into the dough. Bake 18-22 minutes, or until edges are golden. Cool on a wire rack.

Place the caramel and cream in a small saucepan over medium heat. Cook, stirring constantly, until melted.

Pour over the shortbread and spread evenly. Refrigerate about an hour, or until set.

Using an electric mixer on medium speed, beat the butter, sugar, and brown sugar until light and fluffy. Add the cream and vanilla, and mix well. Reduce mixer speed to low and add the flour and salt, mixing until combined. Stir in the chocolate chips.

Using a spatula, spread the cookie dough evenly on top of caramel layer. Place in the refrigerator while making the glaze.

Place the chocolate and butter in a microwave-safe bowl. Heat at half power in 30-second increments until the chocolate melts when stirred. Spread evenly over the cookie dough layer. Chill about 30 minutes, or until set.

Using the edges of the parchment paper, lift the bars out of the pan and onto a cutting board. Use a sharp knife to cut into squares.

Keep the bars refrigerated in an airtight container.