Lightly spoon flour into dry measuring cups; level with a knife.
Combine flour, baking powder, and salt in a large bowl.
Cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Stir in cheese, onion, and sage.
Add milk to flour mixture; stir just until moist.
Turn dough out onto a lightly floured surface; knead lightly 4 to 5 times. Pat or roll dough to a 1-inch thickness; cut with a 2 1/2-inch biscuit cutter.
Place biscuits 2 inches apart on a baking sheet coated with cooking spray. Coat tops of biscuits with cooking spray.
Bake at 425 for 15 minutes or until lightly browned.