Chocolate Cookies

I found these on Pinterest and decided to try them. I really can't believe how wonderful they are. They don't have any flour in them they are very interesting.
I doubled this
1 1/2 cups chocolate chips (divided) I used milk chocolate chips
3 large egg whites
2 1/2 cups powdered sugar (divided)
1/2 cup unsweetened cocoa powder
1 Tablespoon cornstarch
1/4 teaspoon salt

Preheat oven to 350. Spray cookie sheets with cooking spray. Melt 1 cup chocolate chips in the microwave, stirring every 30 seconds. Cool slightly.
Using electric mixer beat whites in large bowl to soft peaks. Gradually beat in 1 cup sugar. Continue beating until mixture resembles soft marshmallow cream.
Whisk 1 cup 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 cup chocolate chips (dough will become very stiff)
Place 1/2 cup sugar in bowl. Roll 1 rounded tablespoon dough into a ball; roll in sugar, coating thickly. Place on prepared sheet. Repeat with remaining dough, spacing 2 inches apart.
Bake until puffed and tops crack, about 10 minutes. Cool on sheets on rack 10 minutes. Transfer to rack; cool.