1Heat oven to 450°. Spray cookie sheet with cooking spray. Mix flour, baking powder, salt, baking soda and mustard in medium bowl. Stir in onions and cheese.
2Mix buttermilk and oil; stir into flour mixture until soft dough forms. Drop dough by 8 spoonfuls onto cookie sheet.
3Bake 9 to 11 minutes or until golden brown. Serve warm.