Preheat oven to 375 degrees F. Line baking sheets with kitchen parchmennt paper or grease lightly with cooking spray.
In medium bowl, mix together flour, soda, and cream of tartar.
In a large bowl, beat butter substitute, applesauce, and sugar substitute until completely blended and mixture is creamy. Add egg whites and vanilla; beat well. Stir in dry ingredients until well blended.
Drop dough, using a cookie scoop or level measuring tablespoonfuls, on prepared baking sheets. Flatten each ball to 3/8 inch thickness, using a cookie stamp or the bottom of a pretty glass dipped in granulated sugar substitute.
Bake in oven for 10 to 12 minutes or until lightly golden browned around the edges. Do not overbake. Sprinkle lightly with powdered sugar substitute.