Preheat your oven to 100°C (210°F) and line two baking sheets with parchment paper.

In a large mixing bowl, whip the room temperature egg whites with an electric mixer on medium speed for 3-4 minutes until soft peaks form.

Gradually add half of the caster sugar, cream of tartar, and vanilla extract to the egg whites, whisking continuously for 1-2 minutes.

Continue adding the remaining caster sugar gradually, increase mixer speed to medium-high and whisk for 6-8 minutes until stiff peaks form.

Gently fold in green food coloring gel until evenly mixed, ensuring not to overmix.

Transfer the green meringue to a piping bag fitted with an open star nozzle and pipe onto the prepared baking sheets.

Decorate each meringue with sprinkles before baking.

Place the baking sheets in the oven and bake for 1 hour, then turn off the oven and leave the meringues inside to cool completely.

Once cooled, carefully peel the meringues off the parchment paper and serve.