Preheat the oven to 400 degrees and line two baking sheets with parchment paper.
Put the egg whites in a large bowl and mix on high until soft peaks (white and foamy). Continue mixing and slowly add 2 cups powdered sugar until stiff peaks are reached (if you flip the bowl upside down, the mixture doesn't move).
Add in the cocoa powder, cornstarch, and salt, and mix on a low speed.
Melt 1 cup of chocolate chips in a microwave safe bowl in increments of 30 seconds until just melted. Add the melted chocolate into the mixture. Stir with a spoon, and then add the remaining half a cup of chocolate chips.
Put the remaining 1/2 cup of powdered sugar on a plate. Take 1 heaping tablespoon of dough, and roll it into a ball. Then, take the ball and roll it in powdered sugar. You want it to be fully coated.
Take the ball and place it on the parchment paper. Repeat with the remaining dough, and allow 2 inches between the balls.
Bake for 10 minutes, and let them cool before eating.
