Preheat oven to 350°F / 180°C (160° fan-assisted) and line a muffin pan with cupcake liners
Sift the sugar, flour, cocoa powder, baking soda, and salt into a bowl and mix together.
Crack the eggs into a separate bowl and add the buttermilk, oil, vinegar, and vanilla. Whisk together until combined.
Add red food coloring to the wet ingredients and mix it in. Tip: It can be easier to put a few tablespoons of the liquid mixture into a cup or small bowl and stir the red food colouring into that first, then pour back into the liquid ingredients. This ensures it incorporates fully and doesn't leave any lumps of unmixed gel colour.
Pour the wet ingredients into the dry ingredients and use a wooden spoon or rubber spatula to stir everything together, just until there are no more lumps. Be careful not to overmix.
Divide the batter into the lined cupcake tin. I like to use an ice cream scoop for this to make sure all the cupcakes are the same size.
Put the cupcakes straight into the oven, don't let them sit on the counter too long before baking, as the baking soda will start to react as soon as it gets wet. Bake for 20-22 minutes or until a skewer comes out clean.
Remove from the oven and let sit in the pan for a few minutes before taking the cupcakes out of the pan and transferring to a wire rack to cool completely before frosting.
Make the Cream Cheese Frosting
Beat the room temperature butter and cream cheese in a stand mixer with a paddle attachment until smooth and creamy.
Add the vanilla and salt, then sift in the powdered sugar and turn the mixer back on, starting on low speed so you don't get a dust cloud of sugar everywhere. Gradually increase to medium-high speed and beat for 1-2 minutes.
You can adjust the amount of sugar to get the frosting consistency you like - the more you add, the thicker it will be. For a softer, spreadable frosting, beat on medium speed just until everything comes together. For a sturdier, pipeable frosting, add more powdered sugar and beat on medium-high speed to add a bit of air until it’s smooth and fluffy.
Notes
Ingredients Notes:Flour - Cake flour will give the best results, but you can also use all-purpose flour if that's what you have at home. Cocoa Powder - Use natural, unsweetened cocoa powder. Food Coloring - Make sure you use GEL red food colouring, not liquid. The liquid kind won't hold the color well as it bakes, and your cupcakes will end up dull or orange. I love this gel red colouring for my bakes. Powdered Sugar - For the cream cheese frosting, I have listed a range for the amount of powdered sugar. This is for two reasons. Firstly, all brands of cream cheese are different, and you may require more or less powdered sugar in your frosting to compensate. Secondly, you can adjust the amount of powdered sugar depending on the consistency of frosting you would like. Add more for a thicker frosting or less for a softer one.