Preheat oven to 400°F/205oC Spray 2 large baking sheets with nonstick spray (or silicon baking mat).
Melt 1 cup chocolate chips in microwave safe bowl or over a double boiler. If using microwave, heat in 30 second intervals and stir in between. Cool slightly.
In a stand mixer with a whisk attachment (or a hand mixer can be used) , beat egg whites until soft peaks form.
Gradually beat in 1 cup powdered sugar. Continue beating until mixture is glossy and thick - resembling marshmallow creme.
In a second mixing bowl, whisk together second cup of sugar, cocoa, cornstarch, and salt together until evenly blended.
On low speed, beat dry ingredients into egg white mixture. Stir in peppermint extract, lukewarm chocolate and remaining 1/2 cup chocolate chips (dough will become very stiff).
Using a small cookie scoop, scoop and roll 1 rounded tablespoon dough into ball. Roll in additional powdered sugar.
Place on prepared baking sheet, spacing 2 inches apart. Bake until puffed and tops crack, about 8-10 minutes. Immediately upon removing from the oven, press 1 chocolate kiss in the middle of the cookie. Cool on sheets on rack for 5 minutes. Transfer to rack to cool completely. Store at room temperature for up to 3 days.