📋 Instructions

1. 1Heat oven and pan — Heat the oven to 175 C (350 F). Line a 23 cm (9 inch) square pan with parchment, leaving a 5 cm overhang. (The overhang lets you lift the slab out for straight cuts.)
2. 2Melt butter with cocoa — Melt 170 g butter in a saucepan over low heat, then whisk in 60 g cocoa for 60 seconds. (Hot butter blooms the cocoa and darkens the color.) Stop when the mixture is smooth and glossy.
3. 3Whisk in sugar and eggs — Off the heat, whisk in 200 g sugar, then 2 eggs one at a time, then 1/2 teaspoon salt. (Adding eggs off heat prevents them from scrambling.) The batter is done when it looks thick and shiny, about 60 seconds of whisking.
4. 4Fold in flour — Fold in 90 g flour with a spatula in 20 strokes. (Stopping at 20 strokes limits gluten and keeps the crumb fudgy.) Stop the moment no dry flour is visible.
5. 5Spread the base — Scrape the batter into the pan and level it with an offset spatula. (An even 2 cm layer bakes uniformly.) The surface should be flat with no high corners.
6. 6Mix the cream cheese swirl — Beat 150 g cream cheese, 40 g sugar, 1 egg yolk and 3 drops orange gel until smooth, about 45 seconds. (Overbeating whips in air and the swirl puffs and cracks.) Stop when no lumps remain.
7. 7Dollop and swirl — Drop 9 spoonfuls of orange batter across the base, then drag a skewer through in 4 passes. (Four passes make a web; more blend the colors to beige.) Stop when the lines are distinct.
8. 8Bake to temperature — Bake at 175 C (350 F) for 32 to 35 minutes, until the edges pull 2 mm from the pan and the center reads 90 C (194 F). (The thermometer reading is the reliable doneness cue.) The top should look set, not wet.
9. 9Cool and chill — Cool in the pan 30 minutes, then refrigerate 2 hours. (Cold fat firms the swirl so the knife cuts clean lines.) The slab is ready when it feels firm at the center.
10. 10Cut into squares — Lift the slab out by the parchment and cut into 12 squares with a warm knife, wiping between cuts. (A clean blade stops cream cheese smearing across the dark crumb.) The edges should be sharp and the swirl visible on each square.