1. Heat oven to 375°F. Lightly grease cookie sheet or line with parchment paper.
2. Beat egg whites with cream of tartar and salt in small bowl until soft peaks form. Gradually add sugar, beating until stiff peaks form. Carefully fold in vanilla and chocolate chips. Drop by teaspoons onto prepared cookie sheet.
3. Place cookie sheet in preheated oven; immediately turn off oven and allow cookies to remain in oven 6 hours or overnight, without opening oven door. Remove cookies from cookie sheet. Store in airtight container in cool, dry place. Makes about 30 cookies.
Always read labels of each ingredient to ensure that they are gluten free prior to use.