Preheat your oven to 300°F (150°C).

Line a baking sheet with a non-stick silicone mat or parchment paper.

In a large bowl, beat the egg whites and cream of tartar with an electric mixer on high speed until soft peaks form.

Gradually add the sugar, a little at a time, beating well after each addition. Stir in the vanilla extract until the mixture forms stiff, glossy peaks and the sugar is dissolved.

Gently fold in the white and dark chocolate chips.

Drop the mixture by tablespoonfuls onto the prepared baking sheet.

Bake for 35 to 45 minutes, or until the cookies are dry to the touch.

Let the cookies cool on the baking sheet for a few minutes before carefully removing them.

Cool completely on a wire rack.

Store the cookies in an airtight container at room temperature.