1 1/3 cups flour
1 cup sugar
1/3 cup packed brown sugar
1/2 cup cocoa
1 tsp. baking powder
1/4 tsp. salt
1/4 cup stick margarine or butter, softened
3 large egg whites, lightly beaten
1 tsp. vanilla
Icing sugar for rolling
Preheat oven to 400°F. In a large bowl, combine flour, sugar, brown sugar, cocoa, baking powder and salt, breaking up any lumps of brown sugar. Stir in margarine until the mixture is well combined and crumbly. Add egg whites and vanilla and stir just until the dough comes together.
Place a few heaping spoonfuls of icing sugar into a shallow dish. Roll dough into 1 1/2 inch balls and roll the balls in icing sugar to coat. Place 2 inches apart on a cookie sheet that has been sprayed with nonstick spray. Bake for 12 to 14 minutes, until just set around the edges but still soft in the middle. Transfer to a wire rack to cool.