Start by pouring the liquid from two cans of chickpeas into a saucepan. Simmer over medium heat until it's reduced to approximately 125g, which may take about 10-15 minutes. Allow it to cool, then refrigerate overnight.

Preheat your oven to 150°C (300°F); for fan ovens, set it at 130°C (275°F). Line your baking sheets with parchment paper.

Once your aquafaba is chilled, measure out 100g and place it in a mixing bowl, adding cream of tartar. Whip on high speed until frothy, about 2-3 minutes. Gradually add the caster sugar until stiff peaks form.

Sift together 100g of ground almonds and 200g of icing sugar into a separate bowl. Fold this mixture into the whipped aquafaba in two parts until smooth.

Transfer the mixture into a piping bag fitted with a round tip. Pipe 2-inch circles onto the prepared baking sheets, leaving space between each.

Allow the piped shells to rest at room temperature for 20-30 minutes until they develop a matte outer shell.

Bake the macarons in the preheated oven for 18 minutes until firm. Let cool completely on the trays.

Combine 200g of icing sugar, 100g of softened vegan margarine, and 1 teaspoon of vanilla extract in a mixing bowl. Beat until fluffy.

Pair your macaron shells by size. Pipe buttercream onto one shell and sandwich it with another.

Store your assembled Vegan Macarons in an airtight container in the fridge for up to 2 days.