Shortbread

1. Preheat the oven to 350F/180C and line a 9X9" pan with foil so the foil overhangs.
2. In a large bowl mix together the flour, sugar, and salt. Add the melted butter and stir gently until fully combined, the crumbs will be moist. Press the dough into the bottom of the prepared pan. Use your clean hand to press the dough down to create an even layer, then use a fork to prick the dough every inch.
3. Bake in the preheated oven for 20-23 minutes, until lightly golden brown.  Let pan cool on a wire rack for 20 minutes. While the shortbread bakes, I prepare the brownie batter and caramel layer. I start by cooking the brownie batter through step one then while it has to cool for 5 minutes I begin the caramel. I have all of the brownie ingredients ready to go so I quickly prepare as I am frequently stirring the caramel, you cannot leave the caramel for too long or you will end up with burned spots. If you prefer you can make the brownie batter first and let that sit aside before preparing the caramel layer.

Caramel

1. In a large heavy bottom, pan add the sweetened condensed milk, brown sugar, sea salt, heavy cream, corn syrup, and unsalted butter. Over medium heat stirring often until mixture registers to 236F/113C to 240F/115C degrees*(see note). This will take about 15- 20 minutes of stirring. Once the temperature is reached take the pot off of the heat. Carefully pour the caramel over the shortbread crust, and use a spatula to spread into an even layer as best as you can.

Brownie

1. In a large pot add the water, butter, sugar, and cocoa powder. Cook on medium heat for 2-3 minutes until it is all combined together, the mixture will look weird and not liquidy enough, but that is fine. Then add the oil and vanilla extract, and mix as best as you can it might look separated that is fine.
2. Take off of the heat, let sit for 5 minutes then add the egg and egg yolk. Whisk to combine.
3. Add the baking soda, salt, and cornstarch, and mix to combine. Gently add the flour by using a spatula to fold in until just combined, just before there are no flour streaks add your chocolate chunks/ chips. Do not overmix, this will affect the end product.
4. Pour into the prepared pan on top of the caramel and use an offset spatula to spread into an even layer to cover all of the caramel and bake for 25-30 minutes. Everyone’s oven is different, for me, the brownies always bake within 25-30. Don't overbake the brownies. You want a toothpick in the center to come out with moist crumbs, not completely dry. Place the pan on a wire rack to cool completely before cutting. Store in an air-tight container on the counter for up to 4 days.