• Preheat oven to 350° F. Line an 8x8 baking dish with parchment paper, overlapping the sides for easy removal, and set aside.

for the shortbread layer-

• In the bowl of a stand mixer, add in butter, sugar, vanilla extract, and flour. (Be sure to fluff your flour before measuring to get an accurate measurement.)
• Mix slowly until a crumbly dough forms. It will look like crumbs in the stand mixer, but when squeezed together in your hands will hold its shape.
• Press dough evenly into bottom of prepared pan. Bake for 18-25 minutes or until edges are just becoming golden. Remove from oven and set aside to cool a bit.

for the caramel layer-

• Combine sweetened condensed milk, brown sugar, and corn syrup in a small saucepan over medium-low to medium heat. Using a rubber spatula, stir frequently, ensuring the mikxture doesn't stick to the bottom and sides of the saucepan.
• Continue heating and stirring until mixture begins to thicken, bubbles up while stirring, and the temperature reads 225° F using an instant read thermometer. This is a low and slow process, so don't rush it or you'll risk either burning the caramel or it separating.
• Remove from heat and vigorously stir in vanilla extract.
• Pour caramel on top of baked shortbread layer and spread to evenly coat, if needed.
• Allow to cool at room temperature for about 2 hours or in the refrigerator for at least an hour.

for the chocolate layer-

• Once caramel layer has set, being making the chocolate layer by adding chocolate chips and heavy cream to a small saucepan over medium-low heat, stirring with a rubber spatula scraping bottom and sides of saucepan frequently.
• Once chocolate is almost completely melted, remove from heat and give it one last stir to melt the rest of the way.
• Immediately pour chocolate mixture over top the caramel layer, sprinkle with salt if desired, and set aside to cool for about 2 hours or in the refrigerator for at least an hour.
• Once completely chilled and set, pull the whole block out of the baking dish using the parchment paper as "handles" and place on flat surface.
• Slice into 16 even squares and serve!