Preheat oven to 225°F (107°C). Line two baking sheets with parchment paper.

Wipe mixing bowl with a little vinegar or lemon juice to ensure it is completely grease-free.

In the bowl, beat egg whites, cream of tartar, and salt on medium speed until frothy and soft peaks form.

Increase speed to high and gradually add sugar, one tablespoon at a time, beating well after each addition.

Continue whipping until the meringue is glossy and holds very stiff peaks. The sugar should be completely dissolved (rub a little between fingers to check for grit).

Gently fold in vanilla extract and mini chocolate chips using a spatula. Do not overmix or the whites will deflate.

Drop spoonfuls of batter onto prepared baking sheets or pipe into swirls, spacing them 1 inch apart.

Bake for 60 to 90 minutes. They are done when they look dry, are pale in color, and lift easily from the parchment.

Turn off the oven and prop the door open slightly. Let cookies cool completely inside the oven (at least 1 hour) to prevent cracking.