Preheat the oven to 210°F (100°C). Line a 9x13 baking sheet with parchment paper.

Prepare a double boiler by filling the bottom with water and heating it until it simmers. In a heatproof bowl, whisk together the egg whites and sugar. Place the bowl over the simmering water, making sure the bottom of the bowl doesn't touch the water.

Whisk continuously until the sugar dissolves and the mixture becomes warm to the touch. This should take about 10 minutes. Remove the bowl from the heat.

Transfer the mixture to a stand mixer (or use a hand mixer) and add the vanilla paste. Beat on high speed for about 5-7 minutes until stiff, glossy peaks form.

Transfer the meringue mixture to a piping bag fitted with a large round tip. Pipe ghost shapes onto the prepared baking sheet, forming small mounds with peaks at the top for the ghost heads.

Bake for 1 hour. The meringues should be crisp and firm to the touch. Once done, turn off the oven and let the meringues cool inside the oven for 1 hour.

Decorate by mixing black food dye with a bit of water to form "ghost eyes and mouths." Use a small brush or toothpick to paint faces onto the cooled meringues.

Store the meringue cookies in an airtight container at room temperature.