Prepare baking trays by lining with non-stick baking paper.
Sift together the ground almonds and icing sugar into a large bowl. Add the 80ml of egg whites and mix together to form a paste. Colour the paste the chosen colour of your macaroons using a gel or powder food colouring and mix well.
Add the egg whites and vanilla extract to the bowl of Kenwood Kmix stand mixer or large bowl.
Begin to whisk the egg whites. Once they reach the soft peak stage turn off the mixer.
Place the caster sugar and water in a small pan. Heat over a low heat until the sugar dissolves. Turn up the heat and bring the sugar syrup to the boil. Using a sugar thermometer heat the syrup until it reaches 110c. At this point remove from the heat straight away. The sugar syrup must not be allowed to heat any higher than 110c or it will ruin the meringue.
Turn the Kenwood Kmix stand mixer on to continue whisking the egg whites. Pour in the sugar syrup very slowly in a thin stream whilst continuing to whisk.
Once all of the syrup has been added continue to whisk the egg whites until they have cooled, this may take 5-10 minutes.
Once cooled, stop whisking. Add 1/3rd of the Italian meringue to the coloured paste and beat in well to loosen the mixture.
Add the remaining 2/3rds of the meringue and using a palette knife fold the mixture together. Take care not to knock the air from the meringue. Mix until the consistency is even. It should still be light and airy but will run from the palette knife in a continuous ribbon.
Fit a large piping bag with a round open nozzle.
Pipe macaroons, 3cm in diameter, evenly spaced onto the baking sheets.
Tap the baking sheet firmly on the work surface and then set each to one side for 1 hour or until a skin has formed on the Macaroon shells and you can touch them with your finger.
Preheat the oven to 120c (fan)/140c/Gas Mark 2.
Bake each tray in the oven for 13-15 minutes.
Once removed from the oven slide the non-stick paper from the baking tray and turn it over so that the macaroons are facing downwards. This helps to stop them from sticking.
After cooling for a couple of minutes remove the macaroons from the paper and place the right way up on a wire rack to cool completely.
To make up the buttercream beat together the softened Stork, icing sugar and vanilla bean paste.
Sandwich together two macaroon shells with a little vanilla buttercream and serve.
Macaroon shells will keep very well in an airtight container unfilled. Once filled they start to absorb the moisture from the buttercream so are best served right away.