Preheat oven: 180°C / 160°C (fan) / Gas Mark 4 / 350°F
In a medium bowl, cream together the butter, sugar and oil, either using a spatula, electric hand mixer or stand mixer, until light and pale.
Beat in the eggs one at a time until fully combined.
Sieve the flour and baking powder into the mixture, gently folding in until just combined.
Stir in the milk, vanilla extract and salt.
Line your cupcake pan with cupcake cases and fill each up to ½ to ⅔ full with batter. This should make 10-12 cupcakes, depending on case size.
Bake in the oven for 15-20mins or until the cupcakes are lightly golden, springy to the touch and an inserted skewer comes out clean from the middle.
Transfer the cupcakes to cool on a wire rack while you make the frosting.