Preheat oven to 350°F (175°C). Line an 8x8-inch square metal baking pan with parchment paper, leaving an overhang on the sides for easy lifting. Lightly butter the parchment.

In a medium heatproof bowl, whisk melted butter and sugar vigorously for 1 full minute until glossy and emulsified. Whisk in eggs and vanilla until pale and thick.

Gently fold in sifted cocoa powder, flour, and salt with a rubber spatula just until no dry pockets remain. Fold in chocolate chips. Spread 85% of the batter evenly into the prepared baking pan, reserving about 3 tablespoons for the top.

In a separate bowl, beat softened cream cheese and sugar until silky smooth. Beat in the egg yolk, vanilla, and orange food coloring until vibrant and uniform.

Dollop spoonfuls of the orange cheesecake mixture across the dark brownie base. Drop the remaining brownie batter in small dollops between the orange spots.

Insert the tip of a wooden skewer or butter knife 1/2-inch into the batter. Gently drag in figure-eight loops to create an intricate marbled swirl pattern. Do not over-swirl!

Bake for 28–32 minutes until edges are set and a toothpick inserted near the center comes out with a few moist fudgy crumbs (never wet batter).

Immediately press edible candy eyes and sprinkles gently into the warm surface while still soft. Let cool completely in the pan for at least 1 hour, then chill for 30 minutes in the fridge for clean bakery-style slices.