Fry bacon in a large skillet over med-high heat til crisp, about 5 minutes. Transfer with slotted spoon to plate lined with paper towels. Spoon off all but 2 tablespoons bacon fat.
Meanwhile, place flour in shallow dish. Season chicken with salt and pepper, dredge in flour, shake off excess.
Add butter to reserved bacon fat in skillet and heat. Cook chicken until browned on both sides, about 4 minutes per side. Transfer chicken to plate, leaving fat in skillet. Cover chicken loosely with foil.
Reduce heat to medium and add garlic and rosemary. Cook about 2 minutes. Add broth and lemon juice, deglazing the pan using a wooden spoon. Simmer until slightly thickened (about 5 min).
Return chicken and bacon to pan and simmer, turning chicken once until sauce is thick and glossy, about 4 minutes.