We really liked some store-bought cookies I found: Whole Foods' Low-Fat Chewy Chocolate Cookies, and I was determined to develop a recipe. Here's what I've come up with, after modifying a similar one I found at A Chef's Help.

4 egg whites
2.5 cups powdered sugar
1 cup cocoa
2 Tablespoon flour
1/3 teaspoon salt
1 Tablespoon water
1 cup mini chocolate chips

Preheat oven to 350°. Line two cookies sheets with parchment paper; grease paper.

With an electric mixer, beat egg whites until they stand up in soft peaks. Sift in sugar, cocoa, flour, salt. Add the water and continue beating on low to blend, then on high for a few minutes until the mixture thickens. Fold in the chocolate chips with a rubber spatula.

Place generous spoonfuls of batter on cookie sheets, spaced 1 inch apart. Bake about 12 min, until tops are cracked but centers are still soft. Transfer to a rack to cool.

Jon says these are the best!