Preheat the oven to 350 degrees F.
In a large mixing bowl, combine flour, cocoa powder, and kosher salt. Whisk together until combined and set aside.
In a separate large mixing bowl, combine eggs, egg yolk, sugar, brown sugar, melted butter, and oil. Whisk together for 2 minutes, until combined. Then add sour cream, vanilla extract, vinegar, and food coloring and continue to whisk until all ingredients are fully incorporated and smooth.
Add flour mixture to the wet ingredients and fold together until just combined.
Spray a 8x8 square baking pan with nonstick baking spray or line with parchment paper.Add brownie batter. Bake for 25-30 minutes, until the edges are set and then center is slightly jiggly.
Allow brownies to cool in the pan for 10 minutes, then turn over onto a wire rack and allow them to cool completely.
Make the cream cheese frosting by adding cream cheese and butter to a mixing bowl and mixing together with a hand mixer until smooth, about 2-3 minutes. Then add powdered sugar, vanilla extract, and pinch of salt. Continue to mix until smooth and fluffy.
Once the brownies have cooled completely, smooth the frosting on top and top with sprinkles (optional).
optional: for the marbled look, add half of the frosting to a separate mixing bowl and add red food coloring and mix together. Dollop white and red frosting on top of the cooled brownies and swirl together.