Preheat oven to 350°.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 4 ingredients in a large bowl; cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Stir in raisins. Add buttermilk; stir with a fork just until moist.
Turn dough out onto a lightly floured surface; knead 3 or 4 times.
Press dough into an 8-inch round pan coated with cooking spray.
Bake at 350° for 30 minutes or until lightly browned. Cool in pan 10 minutes. Cut into 12 wedges.