Preheat oven to 350°.
Mix butter and sugar together with an electric mixer on medium speed for 2 minutes.
Add egg whites and vanilla, mixing well.
Melt 1 cup of the chocolate chips in the microwave or on the stovetop over low heat.
Add to the sugar mixture, mix well.
Next, add the water and mix until combined.
Add flour, baking powder and salt, mix well.
Fold in the remaining chocolate chips.
Cover and refrigerate 2 hours.
Scoop into 1 1/2 inch balls. Roll in between the palms of your hands until smooth and round.
Roll in powdered sugar.
Place on a lined baking sheet about 2 inches apart.
Bake for 10 - 12 minutes or until set.
Remove from oven and cool on a wire rack.