Step 1

In a microwave, melt 1 cup chocolate chips. Stir until smooth. Beat butter and sugar until crumbly, about 2 minutes. Add egg whites and vanilla; beat well. Stir in melted chocolate.

Step 2

In another bowl, whisk together flour, baking powder and salt; gradually add to butter mixture alternately with water. Stir in remaining 1 cup chocolate chips. Refrigerate, covered, until easy to handle, about 2 hours.

Step 3

Preheat oven to 350°. Shape dough into 1-in. balls. Roll in confectioners' sugar. Place 2 in. apart on baking sheets coated with cooking spray. Bake until set, 10-12 minutes. Remove to wire racks to cool.