1. Place chicken breast, bacon, and onion into the instant pot. Use the saute function to cook the chicken and bacon, stirring frequently. 2. Add carrots, celery, ranch seasoning and broth and mix well. 3. Break spaghetti pasta in half to fit into the instant pot if necessary. Press the spaghetti into the broth so the pasta is coated with liquid. 4. Place the lid on the pot and secure it closed. Close the pressure release valve. Set the instant pot to manual, high pressure for 5 minutes. 5. When cooking cycle is complete, quick release the steam and carefully open the pot. 6. Stir in cheddar cheese until completely melted. 7. Stir in half & half until completely combined.