1. Preheat oven to 375°.
2. Weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 7 ingredients (through salt) in a large bowl, stirring with a whisk. Stir in bacon and jalapeño; make a well in center of mixture. Combine buttermilk, oil, and egg in a bowl, stirring well with a whisk. Add buttermilk mixture to flour mixture, stirring just until moist.
3. Place 12 muffin-cup liners in muffin cups; coat with cooking spray. Divide batter among muffin cups. Bake at 375° for 15 minutes or until a wooden pick inserted in center comes out clean. Cool 5 minutes in pan on a wire rack.