Line your baking trays with greaseproof paper or silicone mats. If using greaseproof paper, place your templates underneath the paper (templates are simply pieces of paper with circles printed on them, so you can pipe your macaron shells evenly sized).
Weigh out your ground almonds and icing sugar into a bowl. Sieve both the ground almonds and icing sugar through a fine sieve twice. If you have lots of big almond bits leftover, wizz them in a blender and sieve again.
To make the meringue, start whisking the aged egg whites in a clean dry bowl on a high setting. When the eggs turn into foam, gradually add the caster sugar. Continue until the meringue reaches stiff peaks.
Combine half of the sieved ground almonds/ icing sugar with the meringue, folding them in gently with a spatula until just combined.
Add and fold in the remaining ground almonds/ icing sugar. Once fully combined, use the spatula to press the batter against the side of the bowl rotating it as you go.
Continue this until the batter flows like thick honey. It should continually flow from the spatula allowing you to draw a figure of eight without breaking. Stop mixing as soon as this stage is reached or it will become too liquid.
Transfer the batter into a piping bag. With the nozzle kept at 90° degrees to the tray, pipe your macarons. Remove the nozzle quickly once the template circle is just filled.
Pick up the trays and drop them back onto the surface from approx. 20 cm height to remove the air bubbles from the macarons.
Leave the macarons to dry out at room temperature. It should take 20 minutes to 2 hours depending on the temperature and humidity of the environment. When they’re ready, they will not leave any residue on your finger when gently touched and feel quite dry on the surface (it's an important step, if you don;t dry them out properly, your macarons will burst and crack when baking).
Preheat the oven to 140°C Fan. Place the macarons in the oven and bake for 10-15 minutes, depending on the size of the macarons. You can try one tray first to establish the time needed.
The foot of each should be solid and not move when pushed but they shouldn’t start to colour/ go brown. Leave them to cool before gently peeling them off from the greaseproof paper.
Place the chopped up white chocolate in a bowl. Set it over a pot of simmering water making sure the bottom of the bowl doesn't touch the water. Stir the chocolate until melted.
Take the chocolate off the pot, stir in the cream and let it cool down for a few minutes.
In a food processor, puree the ripe mango until it's smooth and silky.
Add the mango puree to the chocolate-cream mixture and stir to incorporate fully. Add butter while the mixture is still warm and stir until butter melts and it completely incorporated. Place the mixture in the fridge for 2 hours to set.
Pipe generous amounts onto half of the macaron shells and sandwich with the second shell.
Place in an airtight container in a single layer and allow to chill overnight! These White Chocolate & Mango Macarons also freeze well.