Preheat the oven to 180'C.
Whisk together the butter and the sugar. When light in colour and fluffy in texture slowly add the eggs one by one. When all the eggs are incorporated, slowly sift the self raising flour and the baking powder into the butter mixture. Fold the mixture very gently with a spatula. Ensure all of the flour is mixed in well. Split the vanilla pod and scrape all of the seeds into the mixture. Gently stir the vanilla through the mixture. Pour the mixture into a piping bag. Pipe the mix into the cupcake cases 3/4 of the way full.
Place in the oven for 12 minutes. Remove from the oven and allow to cool before decorating.
Place the sugar into a clean pan and put onto a medium heat. Keep moving the pan as the sugar starts to melt. After a minute the sugar will start to turn into a light caramel colour. Keep on the heat until it starts to bubble slightly and has turned to an amber colour. When the mixture is at this stage, remove from the heat and add the butter. Mix the butter and sugar with a spoon until incorporated. As soon as you have added the butter, add the double cream and keep mixing. When the cream is all mixed and the caramel is smooth, place into a small bowl, cover with cling film and allow to cool.
Put the popcorn kernels into a large pan with a lid. Put onto a medium heat for 10 minutes. Remove the lid and check that all of the kernels have been popped.
Remove the popcorn from the pan. In the same pan place the remaining caster sugar. Make a dark caramel using the same method as for the caramel sauce. When the sugar has caramelised, quickly place the popcorn back into the pan and mix well with the caramel to coat the popcorn. Remove the popcorn from the pan onto a piece of baking paper and allow to cool.
When cool place most of the popcorn (leave some whole pieces to fill the cupcakes with) into a plastic sandwich bag and smash with a rolling pin or place in a food processor and blitz until it becomes a fine dust.
Whisk the icing sugar and butter together until light and fluffy. Mix the icing with half of the caramel sauce. Add some of the crushed popcorn for some texture and mix well. Place the icing into a piping bag with a star nozzle
Remove a small part of the cupcake centre with a teaspoon. Fill with the caramel sauce and a piece of whole popcorn. Pipe the icing on top of the cake starting from the outside of the cupcake and working your way in. Finally, sprinkle the cupcake with some crushed popcorn.
«When cooling the caramel, speed the process up by placing the caramel over a bowl of ice and stirring constantly. »