Preheat your oven to 350ºF. Line a 1/4 sheet pan with parchment paper so there is 1" of overhang on all sides.
Melt your butter and chocolate together in a heatproof bowl over simmering water or in the microwave. Let cool until it no longer feels hot to the touch.
Whisk together your sugar, salt, vanilla and eggs in a bowl until just combined.
Sift together the flour and cocoa powder to remove lumps and then set aside.
Add your melted chocolate mixture to the egg mixture and whisk until just combined.
Add your chocolate egg mixture to the flour mixture and stir gently until just combined and no flour lumps are visible.
Pour your batter into the parchment-lined pan.
Spoon alternating dollops of the colored cream cheese batter on top of the brownies and swirl the colors together.
Add some sprinkles if desired
Place the pan in the center of the oven and bake until a toothpick comes out from the center with a few sticky moist crumbs. About 35 minutes.
Remove the pan from the oven and place onto a cooling rack. Place eyeball sprinkles on top of cream cheese layer
Let cool slightly before slicing and serving. Do not cover or the black pupils on the eyeballs will run.