01 -
Preheat oven to 170°C (350°F) for fan-forced ovens or 190°C (375°F) for conventional ovens. Spray a 23×33cm baking tin with oil and line with baking paper, leaving overhang for easy removal. Use clips to secure paper if needed.
02 -
Combine brown sugar, caster sugar, butter and chopped chocolate in a heatproof bowl. Microwave in 30-second intervals, whisking between each until melted and smooth.
03 -
Whisk in eggs and egg yolk until well combined. Add flour, cocoa powder and vanilla extract, then mix until incorporated.
04 -
Pour batter into prepared tin and bake for 25-30 minutes. Allow to cool completely to room temperature.
05 -
In a large saucepan over low-medium heat, cook sugar, stirring gently with a wooden spoon. Allow to come to a boil and continue cooking until it reaches a rich golden color and a temperature of 118°C (245°F). Monitor closely to prevent burning.
06 -
Carefully add hot cream and stir slowly until fully incorporated. Add butter and continue stirring until well combined. Cook on high heat for 5 minutes or until the caramel reaches 120°C (250°F).
07 -
Remove from heat and fold in cornflakes using a wooden spoon until all cereal is evenly coated. Pour mixture over cooled brownie layer and spread evenly.
08 -
Allow to set at room temperature for about 30 minutes, then refrigerate for 2 hours until completely firm.
09 -
For clean cuts, run a large sharp knife under hot water, dry it, then slice into 20 squares (4×5 grid). Serve chilled or at room temperature.