1. Preheat oven to 250°F.
2. Put egg whites into the clean bowl of a standing mixer fitted with a whisk and beat at medium-low speed until frothy ~ 2 minutes.
3. Add salt and gradually increase speed to high, beating until whites form stiff but not dry peaks, ~ 1½ minutes.
4. Reduce speed to medium.
5. Add vanilla, then add sugar a few tablespoons at a time.
6. Continuing to beat whites until sugar dissolves and they are smooth and glossy, ~ 2 minutes.
7. Divide whites into two batches.
8. Gently fold chocolate chips and, if you like, pecans, into the whites with a rubber spatula.
9. Take care not to deflate the whites.
10. Drop meringue by the tablespoonful onto parchment-lined cookie sheets, spacing them about 1" apart.
11. Bake for 45 minutes, then turn off oven, leaving cookies inside the oven overnight or until completely cool, at least 4 hours.
12. Remove cookies from oven and store in airtight containers for up to 1 month.
YIELDS: 48 cookies