In a large bowl, beat margarine or butter with an electric mixer on medium to high speed for 30 seconds. Add The sweetening of your choice (Splenda or regular sugars), baking powder, baking soda, and salt.
Beat until combined, scraping side of bowl occasionally.
Add egg whites and vanilla; beat until combined. Beat in as much of the flour as you can with the mixer. Using a wooden spoon, stir in any remaining flour. Stir in cashews and butterscotch chips.
Drop dough by rounded teaspoons 2 inches apart onto an ungreased cookie sheet.
Bake in preheated oven for 8 to 10 minutes or until edges are lightly browned. Transfer cookies to a wire rack; let cool. Makes about 48 cookies.
Layer cookies between waxed paper in an airtight container; cover. Store at room temperature for up to 3 days or freeze for up to 3 months.