1. Heat your oven to 160C fan-forced (180C conventional). Grease and line the bases of 2 x 24cm round baking tins. With a stand mixer fitted with a paddle attachment, cream the butter and sugar together. Add vegetable oil, eggs, milk and vanilla and mix to combine.

2. Sift the flour, cocoa, baking powder and bicarb into a separate bowl, then add the salt and mix together. Add dry ingredients to the wet and mix on low speed until just combined. Add 200ml of boiling water and mix for 30 seconds to combine. Divide the batter between the two cake tins and place on the same rack of your oven. Bake for 30-35 minutes until a skewer inserted into the cake comes out clean. Allow to cool for a few minutes, then turn out onto a rack and cool completely.

3. For the icing, combine ingredients in the clean bowl of a stand mixer fitted with the whisk attachment. Combine on low speed for 1 minute, then beat at high speed for a further minute.

4. To assemble cake, spread a layer of icing on one cake and invert the other on top. Spread top of the other cake generously and cover sides of the cakes as well. Scatter with sprinkles to serve.

Adam's tip Dutch-process cocoa powder is much darker in colour than other types of cocoa powder and will give your cake and icing a rich, luxurious colour. Look for it on the labels of major brands.