Preheat oven to 100 degrees C and line a baking tray with baking parchment.
Place egg whites in a clean bowl and using a wire whisk beat until foamy. Add the cream of tartar and which until mixture forms soft peaks. Gradually add the sugar, one tablespoon at a time, while whisking constantly. Whisk until stiff peaks form and mixture is completely smooth and glossy. Finally, mix in the vanilla.
Spoon meringue into a piping back with a #12 plain round tip. Pipe into ghost figures on the prepared baking tray. Place two silver balls in each as eyes.
Bake in the preheated oven for 1 hour. Turn off oven and leave in the oven 8 hours or overnight. Enjoy!