To make the cupcakes

Preheat the oven to 350°F (177°C). Line the muffin pan with cupcake liners.

In a small bowl, whisk together flour, baking powder, baking soda and salt. Set aside.

Cut the vanilla pod lengthwise and scrape the seeds inside.

In a mixing bowl with paddle attachment, or using a handheld mixer, beat butter and sugar until fluffy, 1-2 minutes. Add eggs, buttermilk, scraped vanilla beans and vanilla extract and mix well, about 3 minutes. Stir in the flour mixture and mix until everything is well combined, 2-3 minutes.

Divide the batter into 12 cupcake cups and bake for 15-18 minutes, or until the inserted tooth pick comes out clean. Let the cupcakes cool for 5 minutes in the tin and then transfer to wire rack to cool completely.

To make the Swiss meringue buttercream

In a double boiler, whisk together egg whites and sugar until sugar melts and the mixture reaches 160°F (70°C) stirring continuously, about 5 minutes. Transfer the mixture into clean, fat-free mixing bowl with a whisk attachment. Whisk on low speed for a minute, then slowly increase the speed to medium high and beat until hard peaks form and the mixture is cool to touch, about 10 minutes.

Cut the vanilla pod lengthwise and scrape the seeds inside.

Switch to a paddle attachment. Slowly add butter one cube at a time with scraped vanilla beans. Make sure the butter is fully incorporated before adding the next one. The mixture might curdle, but don’t panic. Continue to beat the mixture until smooth. (When the frosting reaches the right consistency, you will start hearing slapping sound.)

Transfer the frosting into a pastry bag with decorative tip and frost the cupcakes nice and tall. (I used Wilton 2D tip.)