** Recipe from 
divine baking **
* 1 1/2 c. bittersweet chocolate chips (about 9 oz.), divided                                                              
* 3 large egg whites, room temperature                                                              
* 2 - 2 1/2 c. powdered sugar, divided
* 1/2 c. unsweetened cocoa powder                                                              
* 1 Tbl. cornstarch                                                              
* 1/4 tsp. salt
                                                               
 
                                                                        
                                                          
                                  
Heat
 oven to 350°. Spray 2 large  baking sheets with nonstick spray. Microwave 1
 c. chocolate chips in glass  bowl, stirring twice, about 2
 min. Cool slightly.
Using
 electric mixer, beat whites in  large bowl to soft peaks. Gradually 
beat in 1 c. powdered sugar.  (Add more for sweeter cookies.) Continue  beating until 
mixture resembles soft marshmallow creme.  Whisk 1 c. powdered  sugar, cocoa, cornstarch, and salt in medium bowl to blend. On low  speed, beat dry ingredients into meringue. Stir in lukewarm chocolate  and 1/2 c. chocolate chips (dough will become very stiff).  Place
 1/2 c. sugar in bowl. Roll 1  rounded Tbl. dough into ball; roll
 in powdered sugar, coating thickly.  Place on prepared sheet. Repeat with 
remaining dough, spacing 2"  apart. Bake until puffed and tops crack, about 10 min. Cool on  sheets 10 min. Transfer to rack; cool.