Drain the brine/liquid from a 400g tin of chickpeas into a saucepan. Reduce the liquid (uncovered) on low-medium heat for about 10 minutes until reduced to about 2/3. Leave to cool then refrigerate overnight.
Using a stand mixer (or with electric hand beaters), whisk the aquafaba and cream of tartare in a large bowl, adding the caster sugar gradually once it starts to foam. Continue to whisk, gradually on high speed for 10 minutes or until the aquafaba starts to form firm, glossy peaks. If using, add a good pinch of pink powdered food colouring.
Sift the ground almonds and icing sugar into a large bowl, putting aside any leftover bits of almonds for decorating desserts later. Add the whipped aquafaba and, using a good flexible spatula, mix the ingredients together until combined. Beat out any air using pastry scraper, continuing back and forward until the batter is glossy and falls off the scraper. Transfer the batter to a piping bag with a plain tip (8mm).
Line 2 flat baking trays with baking parchment (I prefer this to a silicone mat, as it's easier to produce feet). Pipe out small rounds, leaving enough space between each (they will spread in the oven slightly) .
Leave the trays out to air for about 30 minutes until they are quite hard to the touch. If still too soft, leave out for longer. Preheat the oven to 130°C/110°C fan/250°F/Gas 1/2.
Bake each tray separately for 15 minutes. Turn the oven off and leave the tray in the oven with the door open for a further 15 minutes (this sounds cumbersome but after experimenting was the best way for this recipe). Leave to cool.
For the filling: Arrange the macaron shells into pairs and marry each couple together by piping out one half with raspberry jam, top with the other shell then set aside in the fridge for 24 hours. (I heated up a quarter of a jar of raspberry jam with a few lemon verbena leaves and left the jam to cool).