Preheat the oven to 230°F (110°C/ fan 90°C) and line a baking tray with greaseproof paper.
Drain the chickpeas and add the chickpeas brine (aquafaba) into a large clean bowl. Add the cream of tartar to the bowl, too.
Whisk with a stand mixer or an electric whisk to med-high for approximately 5-6 minutes until it's more than doubled in size, white and foamy. Make sure you mix until you get stiff peaks.
Start adding the icing sugar very slowly, one tablespoon at a time, and continue until all the sugar has been added. By the end, you should have a beautiful glossy mixture!
Transfer the meringue mixture into an icing bag with a large round plain nozzle and pipe into spooky ghost shapes.
Place in the oven and bake for 2 hours. Do NOT be tempted to open the oven! After 2 hours, turn the oven off and leave the ghosts to cool in the oven for at least another hour (better if you can leave them longer or overnight).
When the ghosts are completely cooled, melt the chocolate, and using a little piping bag, pipe the spooky little eyes (if you don't have a small piping bag, a great trick is to use a toothpick - simply dip the toothpick in the melted chocolate and use it as a pencil to make the eyes).
Keep the meringue ghosts in an airtight container for up to a week (if they ever last that long!).
Notes
Note 1: If you have time to spare, you can make your own aquafaba (see how in the instructions above the recipe card).Note 2: You can try using 1/2 teaspoon vinegar or lemon juice if you cannot find the cream of tartar or you don’t have it at home.
*Nutrition information is a rough estimate per ghost.