For the Red Velvet Traybake
Preheat the oven to 180°C and butter a 33 x 46cm half-sheet pan. Then set aside.
In the bowl of a stand mixer or in a medium bowl with a handheld electric mixer, cream the butter and sugar together until light and fluffy.
Add the eggs, one at a time, followed by the buttermilk, food coloring, vanilla extract and vinegar.
Whisk together flour, cocoa powder, baking soda, and salt, then fold into the batter.
Spread evenly in the pan and bake for 18 to 20 minutes.
Let cool completely in the pan before frosting with cream cheese frosting.
Store in an airtight container in the refrigerator for up to 3 days.
For the Cream Cheese Frosting
In a large bowl, using an electric mixer on medium-high, cream together the cream cheese and butter.
Once light and fluffy, add in the icing sugar and vanilla, whipping until it is smooth and creamy.
This can be stored covered in the fridge for up to 4 days.