In a small bowl, whisk together the flour and salt.
In a large bowl, place your eggs, egg yolks, sugar, oil and vanilla extract. Mix together using a hand held mixer for about 6-8 minutes until well mixed. This is what will give you a thin crust on top!
Place a small saucepan with about an inch of water over medium/low heat until it begins to simmer. Place a heat proof bowl over it and melt your butter and chocolate together until smooth. Take off the heat.
Add in your cocoa powder to the butter and whisk until smooth.
Pour this chocolate mixture into your sugar mixture and whisk until smooth.
Fold in your flour mixture and mix until there are no more flour pockets.
Pour the brownie batter on top of the funfetti oreo layer. Bake for 45-50 minutes. The top should have crackled and a toothpick inserted will come out with a few crumbs. While still warm, you can sprinkles over extra sprinkles on top!
Let cool for several hours until you slice it into bars.