Pound chicken breasts to ¾ inch thickness. Sprinkle both sides generously with salt and pepper and set aside.
Chop bacon and onions. Cook bacon in large skillet over medium heat until crisp. Remove from skillet and drain on paper towels. Leave bacon grease in skillet.
Add chicken and cook until well browned on both sides, about 5 minutes. Remove from pan and set aside.
Add onion to skillet; cook 5 minutes or until tender. Stir in apple butter. Bring to a simmer over medium heat.
Return chicken to skillet, turning to coat with sauce. Cover and cook 4 to 5 minutes or until internal temperature reads 165°F.
Place even amounts of bacon on top of each chicken breast; sprinkle chicken with cheese. Cover; let stand 3 minutes or until cheese is melted.
Serve bacon and melted cheddar chicken breasts topped with apple butter sauce.