Preheat the oven to 325°F. Spray a 9X9- inch pan with baking nonstick spray. Line the bottom and 2 sides of the pan with parchment paper and spray again.
In a medium bowl, sift the flour and cocoa powder. Mix in the cornstarch and salt and set aside.
¾ cup All-purpose flour, 1 cup Unsweetened cocoa powder, 1 tablespoon Cornstarch, ¾ teaspoon Salt
Using a mixer with a whisk attachment, beat the sugar, eggs, and egg yolk on high speed for 5 minutes. It will become pale in color. Stir in the vanilla, oil, and melted butter and mix on low until just combined.
2 cups White granulated sugar, 3 Large eggs, 1 Egg yolk, 2 teaspoon Pure vanilla extract, ½ cup Oil, ½ cup Unsalted butter
Add in the dry ingredients and mix on low until just combined. Take off the mixer. Pour in the chocolate chips and chopped snickers. Use a rubber spatula to fold in the mix ins.
1 cup Semi-sweet chocolate chips, 1 cup Chopped Snickers
Pour the brownie batter into the pan. Use a teaspoon to dollop salted caramel on top of the brownie batter. I used 12 teaspoons. Use a butter knife to very lightly swirl it on top.
Bake for 40-50 minutes. Bake until the edges are set and the middle is under baked. If you stick in a toothpick it should come out with fudgy brownie on it. If it is pure brownie batter, bake for another 5 minutes and check again.
Top the brownies immediately with extra chopped Snickers. Let the brownies cool on a cooling rack. The caramel will melt and cause holes on top of the brownies. Pour extra caramel on top of the brownies. It will sink in the holes!