Preheat the oven to 180C/356F. Place cupcake liners in 10-11 X 80ml capacity muffin tray holes.

Whisk the flours and baking powder or soda in a medium mixing bowl.

In a smaller bowl, whisk together the milk and sour cream and set aside.

Add the butter, oil and sugar to your stand mixer with the beater attachment (you can also use a hand beater) and beat until light, fluffy and aerated. See the body of the post for extensive tips on creaming butter and sugar – this is crucial to a successful, non-oily cupcake.

Scrape down the bowl as often as necessary.

Once the butter and sugar are properly creamed, add one egg and beat on low until incorporated. Add the remaining egg and repeat, scraping down the bowl in between.

With the mixer on low, add about 1/3 of the flour and allow it to incorporate. Add ½ of the sour cream milk mixture, then repeat. Scrape down the bowl then finish with the last 1/3 of the flour. Add the vanilla extract/paste and a pinch of salt if you’re using unsalted butter.

Divide the mixture evenly between 10-11 lined muffin holes. I find the baking powder version makes 10 muffins, while the baking soda version makes 11.

Be sure not to over-fill the muffin liners – 2/3 – ¾ full is perfect.

Bake the cupcakes for 20-25 minutes or until golden brown and cooked through. They should be flat on top and not domed, but light and fluffy. See troubleshooting notes for any cupcake explosions, flat cupcakes or oily cupcakes.

Allow to cool completely before icing.

Sift the icing sugar and cocoa together in a medium mixing bowl.

In another medium mixing bowl, beat the butter with your hand beaters until softened and lightened.

Add the icing sugar mixture in increments, beating the mixture as you go. It will be quite thick and might not process all the way so add 1 tablespoon of milk at a time until you reach your desired consistency.

In my experience, it’s best to work quickly with buttercream. Don’t spend too long beating it and don’t add too much milk or it will begin to split.

Ice the cupcakes once completely cooled. Buttercream is best fresh, in my opinion, so try to ice them on the day you are serving them.