Preheat oven to 350°F/175°C. Line an 8x8 pan with foil and set aside.
In a small saucepan melt your butter.
In a large jug, whisk together the sugars, vanilla, and salt. Add the egg and whisk until smooth.
Pour the butter into the jug and whisk.
Pour in the flour and baking powder, whisk until there are no more pockets of flour but don't overmix.
Fold in your sprinkles.
Pour the batter into the bottom of your pan. Place your oreos on top.
Brownies
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.
Notes
Butter: I use European style butter, like Kerry Gold, in my recipes. This will make your finished bake much creamier and richer.Salt: If you don't have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt.Cocoa Powder: I am using dutch process cocoa powder for this. If you live in Europe, this is just regular cocoa powder. Sprinkles: I don't recommend using nonpareils (the little circular balls) as they'll bleed quite a lot. Vegetable Oil: Use a neutral oil like canola oil, vegetable oil, or rapeseed oil Storage: Keep them in an airtight container, if you keep them at room temperature they’ll last about 3 days but in the fridge they’ll last about 5 days. Slicing: The brownies will continue baking when you remove them from the oven, so let them cool completely before you slice them.