In a medium sized bowl add the red velvet cake mix, flour, cornflour, baking soda and salt. Whisk until everything is well combined and place to one side.
In a stand mixer or a large bowl using an electric hand mixer beat the butter and sugars until light and fluffy. 3 minutes on a high speed.
Add the egg and vanilla and mix until combined.
Add the red food colouring - I used 2 teaspoons but add as much or as little as you like until you have the desired shade of red, then mix.
Add the cake & flour mix to the wet ingredients and on a low speed beat until everything has just come together, scraping the bottom of the bowl as needed.
Take the batter - it will be soft and sticky at this point - and place it in the fridge for at least 90 minutes or up to 3 days.
When you are ready to make your cookies preheat your oven to 180C/350F/Gas mark 4 and line a large cookie sheet with baking parchment or a silicone baking mat.
My cookies were 2 tablespoon size scoops - this is a great size, big enough to satisfy but small enough that you get a decent number of cookies.
Don't flatten the batter leave it in balls and give them at least 3 inches space to spread.
Depending on the speed of your oven and how crispy you want your cookies bake them for anything between 9-12 minutes. I found 11 minutes was the sweet spot for me. Crispy edges soft and chewy in the middle. But beware my oven is really slow!
Take the cookies out of the oven and cover them in any chocolate decorations at this point as they are hot they will stick.
Allow them to sit on the baking sheet for at least 5 minutes then transfer them to a wire rack to fully cool down.
Kept in an airtight tin at room temperature these cookies are good for 5 days, though the crispy edges disappear on day 3.