Melt the butter in a bowl (bain marie) where the bowl should not be touching the boiling water
Stir in the caster sugar and 2 tsp vanilla extract and mix with a wooden spoon until they are all incorporated
Add the cocoa, red food coloring and vinegar and mix with a mixer until everything is incorporated
Add 4 eggs and beat until you get a smooth texture
Add the flour and salt and mix gently
Get a tray (medium size) and line it with non stick baking parchment
Pour in the batter, leaving about 5 tbs behind
Meanwhile, preheat your oven to 175C (350F)
Put the cream cheese, icing sugar, 2 remaining eggs and 1/2 tbsp vanilla extract in a bowl and beat on medium speed in a mixer until you get a smooth texture
Gently pour the cream cheese mixture on the red velvet
Put the remaining red velvet in drops on top creating uneven draws
Ok, mine was not very artistic...
Place it in the over and bake it for about 35 minutes. Remove it and leave it to cool for about 30', then place it in the refrigerator for 1 hour
Cut it to the shape you like and enjoy!