Heat olive oil in a large pot. Brown chicken breasts on all sides, then remove and set aside.
Add butter, celery, carrots, onion, and garlic to the pot. Cook for a few minutes until softened.
Add pepper, Sazon, Italian seasoning, garlic powder, and paprika. Cook ~1 minute until fragrant.
Stir in flour thoroughly, then gradually add chicken broth, stirring constantly.
Return chicken to the pot and cook ~15 minutes until chicken is cooked through. Remove chicken, shred or chop into bite-sized pieces, and return to pot.
Stir in chicken bouillon and noodles. Cook until noodles are tender.
Adjust seasoning to taste and serve hot.
Tip: Leftovers thicken beautifully overnight—just add a splash of broth when reheating if needed.