1. Preheat your oven to 170°C (340°F). Line a 12-cup muffin tin with cupcake liners.
2. In a medium bowl, whisk together the plain flour, cocoa powder, baking soda, and salt. Set aside.
3. In a large bowl, cream together the softened butter and caster sugar using an electric mixer on medium speed until light and fluffy, about 2-3 minutes.
4. Beat in the egg until well combined. Add the vegetable oil, vanilla extract, and red gel food coloring, mixing until evenly incorporated.
5. Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk, starting and ending with the dry ingredients. Mix until just combined. Be careful not to overmix.
6. Divide the batter evenly among the cupcake liners, filling each about two-thirds full. Bake in the preheated oven for 20-22 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.
7. Allow the cupcakes to cool in the tin for about 5 minutes, then transfer them to a wire rack to cool completely.

Cream cheese frosting

1. In a medium bowl, beat together the softened butter and cream cheese until smooth and creamy.
2. Gradually add the sifted icing sugar, mixing on low speed until well combined.
3. Stir in the vanilla extract until smooth.
4. Once the cupcakes are completely cool, frost them with the cream cheese frosting using a piping bag or a spatula.
5. Enjoy your delicious red velvet cupcakes with cream cheese frosting!