Preheat your oven to 350 degrees Fahrenheit (175 degrees Celsius) and grease a 9-inch bundt pan generously with butter, and set aside.
In a large bowl, combine the sugar, flour, cocoa powder, baking powder, baking soda and salt with a wire whisk.
Measure the buttermilk and vegetable oil into a large liquid measuring cup.
Add the eggs and vanilla to the milk mixture, along with the red food colouring, and whisk all the wet ingredients together with a fork.
Add the wet ingredients to the dry ingredients and whisk together just to combine (until no streaks of flour remain and the batter is a smooth, even red colour.
Slowly add the boiling water, whisking constantly until the batter is smooth and everything is combined.
Pour the batter into the prepared bundt pan and bake for about 35-40 minutes or until the a toothpick inserted into the middle of the cake comes out clean.
Let cool in the pan on a wire rack in the pan until almost cooled completely to room temperature.
Place an inverted plate over the bottom of the bundt cake and flip gently. The cake should slide out of the pan easily and sit nicely on the plate. Trim the bottom of the cake slightly, if necessary, to ensure it will sit flat.