• Measure all ingredients.
• Place egg whites in a bowl, whisk the egg whites on a medium until foamy.
• Slowly add in the castor sugar.
• Continue to beat until the egg whites are glossy and have stiff peaks.
• Add in the yellow and green colouring and beat to mix in.
• Sift the almond meal and confectioners sugar into the egg white.
• Slowly fold the dry ingredients into the meringue, until the batter flows of the spatular with like lava and can form a figure 8 a few times without breaking.
• Fill into a piping bag and pipe 1 inch (3.5cm) rounds onto baking paper or silicon mat.
• Set aside to rest for 15-45 minutes, until a skin has formed on the macarons and touching them with your finger will not cause them to stick to your finger.
• Heat oven to 150c/300F. The oven temperature may take some testing to get right.
• Place in the oven for 20 minutes. If your oven has heat spots, it is best to flip the pan every 5 minutes while baking.
• Remove the macarons if they no longer move when pushed on their feet.

Pistachio Buttercream

• Crush pistachios by placing in a food processor or bullet blender. If roasted pistachios aren't available, this can be done by by placing the pistachios in a small pan on low heat for a few minutes, watch them carefully as they can burn easily. They'll be done when they start to change in colour and have a fragrant smell. Remove and place in a bowl to cool down completely before crushing.
• Place butter and sugar in a bowl of a mixer. Beat until smooth and creamy.
• Add in the crushed pistachios, vanilla and colouring and beat until well combined and smooth. A teaspoon of milk can be added to the buttercream to smoothen it out further if it is too stiff.

Assembling

• Match each shell to a shell of a similar size.
• Fill pistachio buttercream into a piping bag fitted with a round tip. Pipe a small mound into the centre of the one side of each shell, leaving room on the edges.
• Place the top shell onto the bottom filled shell and press gently.
• Put macarons into an airtight container and store in the fridge for 12-24 hours. This will mature the macarons making giving it a better texture and flavour.