In a large pot or Dutch oven, heat olive oil over medium heat. Add diced onion and sauté for about 5 minutes, until translucent. Add minced garlic and cook for an additional 1 minute until fragrant.
Add the boneless, skinless chicken breasts to the pot, along with chicken broth and water. Bring the mixture to a boil.
Once boiling, reduce heat to medium-low and cover. Let the chicken simmer for 15 minutes, or until fully cooked and easily shredded.
Remove the chicken from the pot and shred it using two forks. Return the shredded chicken to the pot.
Stir in the Ranch dressing mix, dried thyme, salt, black pepper, and frozen mixed vegetables. Let it simmer for 5 minutes.
Add the egg noodles to the pot and cook according to package instructions, usually around 8-10 minutes until tender.
Once the noodles are cooked, stir in the heavy cream and simmer for an additional 2-3 minutes. Adjust seasoning if needed.
Serve hot, garnished with fresh parsley if desired.