METHOD
1. Preheat the oven to 170C/325F/gas 3. Line a muffin tin with paper muffin cases or use paper cups on a baking tray.
2. Sift the flour with the baking powder into a large bowl. Add all the other sponge ingredients. Beat with a handheld mixer or in a standing mixer with the paddle attachment for a couple of minutes, until the batter becomes creamy and smooth.
3. Spoon it into the prepared cases filling them halfway up at the most. Bake for 20-25 minutes until the sponge springs back when lightly pressed.
4. In the meantime make the buttercream: place the egg whites and sugar in a bowl over a bain-marie or a pan with barely simmering water; the bowl should not touch the water. Using a hand whisk (it’s hard work) or a handheld mixer beat the mixture until the sugar melts completely, about 10 minutes. Check by rubbing a little mix between your fingers to see if there are no sugar crystals discernible.
5. Transfer the mixture to a standing mixer bowl with a balloon whisk or continue beating at high speed with the handheld, for another 10-15 minutes, until the mix cools down and stiff peaks form.
6. Continue beating and start adding the butter by a tablespoonful. At one point the cream will look curdled but ignore it and keep on; it will become smooth again after 5 more minutes of beating.
7. Beat in the vanilla seeds and the split pods to maximise the flavour; remove the pods before piping the buttercream. Transfer it into a piping bag with a large star nozzle. Chill if you’re not using it immediately but bring it back to room temperature again before piping.
8. Prepare the chocolate filling: chop the chocolate into small pieces and set aside.
9. On the hob: place the cream in a small pan, stir in the icing sugar and the liqueur or essence and bring to the boil. Immediately add the chocolate and take off the heat.
10. In the microwave: place the cream in a bowl, stir in the icing sugar and the liqueur or essence and microwave on full power for about 2 minutes, until it starts to boil. Immediately add the chocolate and remove the bowl from the microwave.
11. Let the mixture stand for a minute, then stir it until blended. Leave it to cool down for a few minutes.
12. Punch holes in the cupcakes with a cupcake corer or use a long piping nozzle to create craters. Spoon the chocolate into the openings or squirt it in with an icing syringe. Pipe the buttercream over the tops generously and decorate as you wish.