Preheat oven to 400°.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, and salt in a bowl; cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Combine parsley, 1/3 cup milk, and yogurt, stirring with a whisk. Add to flour mixture; stir just until moist.
Turn dough out onto a floured surface; knead lightly 3 times. Pat dough to a 3/4-inch thickness; cut with a (2-inch) biscuit cutter. Place on a baking sheet coated with cooking spray; brush with 2 teaspoons milk. Bake at 400° for 18 minutes or until lightly browned.