Melt 1 cup of the chocolate chips, stirring until smooth. I normally use the microwave, but you can use whichever method you prefer. Set aside.
In a large mixing bowl, add butter and granulated sugar and beat with a hand mixer until crumbly, 1-2 minutes. Add in egg whites and vanilla extract, beating to mix. Add in melted chocolate and mix well.
In another mixing bowl, add flour, baking powder, baking soda and salt, stirring to combine.
Add half of flour mixture to the chocolate mixture, mixing to combine, then add in half of the water. Mix, then repeat with remaining flour mixture and water.
Stir in remaining 1/2 cup chocolate chips. Cover mixing bowl with plastic wrap and refrigerate 2 hours or more.
Preheat oven to 350 F degrees, line a baking sheet with parchment paper, and add powdered sugar to a shallow bowl; set aside. Scoop and roll dough into balls, about 1.5 Tbsp each, then roll balls in powdered sugar.
Place 2 inches apart on prepared baking sheet and bake 11-13 minutes. Let cookies sit on baking sheet for 3-5 minutes after baking, then transfer carefully to a wire rack to cool.
Cookies will last about 1 week (covered in an airtight container).