Preheat your oven to 160β (140β if you're using a fan oven). Line an 8x8-inch tin with baking paper.
In a large bowl, mix together the melted butter, caster sugar and light brown sugar.
Stir in the eggs and vanilla extract.
Add all of the flour and the cocoa powder. Mix well to make a smooth, thick blondie batter.
Add the red food colouring, starting with around ΒΌ teaspoon and adding more if needed.
Fold in the white chocolate chips.
Transfer the batter to your lined tin and spread out evenly. Bake for 35-40 minutes, until the edges look firm and are pulling away from the tin slightly. The middle should look baked but still have a slight wobble.
Leave the blondies in the tin to cool completely then put them in the fridge for 3-4 hours to set. This will make the gooey centre turn firm and fudgy.
Once set, drizzle some cream cheese frosting on top then cut into squares and enjoy!