In a medium saucepan, heat white granulated sugar over medium heat, whisking continuously until the sugar melts and turns a rich amber color. Once melted, add cubed unsalted butter and whisk until fully incorporated. Carefully add heavy cream, salt, and vanilla extract, stirring well. Allow the mixture to simmer for about 3 minutes, then remove from heat. Cool the salted caramel for at least 30 minutes before using.

Preheat your oven to 350°F (175°C). Grease a 9x9 inch baking pan and line it with parchment paper for easy removal later. In a bowl, whisk together all-purpose flour, unsweetened cocoa powder, cornstarch, and a pinch of salt.

In a mixing bowl, beat together powdered sugar, large eggs, and egg yolk until the mixture is creamy and fluffy. Gradually mix in melted butter, oil, and pure vanilla extract to enhance flavor.

Slowly fold the dry ingredients into the wet mixture, combining gently until no dry flour remains. The brownie batter should appear thick and glossy at this stage. Lastly, fold in semi-sweet chocolate chips for rich bursts of chocolate flavor.

Pour half of the brownie batter into the prepared pan and spread it evenly. Drizzle half of the cooled salted caramel on top, making sure to distribute it evenly over the batter. Pour the remaining brownie batter on top, smoothing it out to completely cover the caramel layer below.

Place the assembled pan in the preheated oven and bake for 40 to 45 minutes. The brownies are ready when a toothpick inserted into the center comes out with moist crumbs.

Once baked, remove the salted caramel brownies from the oven and allow them to cool completely in the pan. Once cool, poke holes in the surface of the brownies using a fork and drizzle the remaining salted caramel over the top.