In a medium bowl, sift the flour and baking powder. Add the sugar and salt and whisk to combine.

In a second mixing bowl, whisk together the eggs and vanilla beans until just combined. Add the buttermilk, butter and oil and whisk to combine.

Tip the flour mixture into the wet ingredients and use a whisk to gently mix until combined and smooth.

Bake for 16-18 minutes until a toothpick comes out with just a crumb or two attached.

Transfer to a wire rack to cool.

In a small saucepan over low-medium heat, whisk together the milk, half of the sugar and the flour. Continue to heat and whisk gently but regularly for another 3-4 minutes until you have a very thick paste (like thick pudding).

Transfer it to a plate, spread it out to about 1cm thick, then cover it with plastic wrap pressing the plastic wrap to the surface. Let it cool to room temperature before using (you can speed this up in the fridge but make sure it’s not cold when you use it).

In a stand mixer with paddle attachment, beat the butter and remaining sugar for about 5 minutes on medium-high speed or until very light and creamy – scrape down the sides of the bowl every so often.

Meanwhile, use a paring knife to cut the vanilla bean in half lengthwise, then use the back of the knife to scrape out the seeds.

Add the vanilla seeds and salt to the butter mixture and beat for 20-30 seconds to combine.

Now add the milk paste mixture a dessert spoonful at a time, beating on low-medium speed for about 30 seconds between each. Again, scrape down the sides often.

Now beat for a good 5-6 minutes on medium-high, until it looks creamy, thick and smooth. If it looks like it’s splitting, just keep beating, it will come together.

Transfer the buttercream to a piping bag and pipe or spread with a spatula onto the top of the cooled cupcakes.

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