Heat the olive oil in a large pot over medium heat. Add the chopped onion and minced garlic, and sauté for 3 to 5 minutes until translucent and fragrant.

Add the whole chicken, season with salt and pepper, and brown lightly on all sides for 5 to 7 minutes.

Incorporate the sliced carrots and chopped celery, stirring well for an additional 3 to 5 minutes.

Pour in the chicken broth, add the bay leaf and dried thyme, and bring to a rolling boil.

Reduce the heat to low, cover the pot, and let simmer for about 30 minutes.

After 30 minutes, add the diced potatoes and continue to simmer uncovered for another 20 to 30 minutes until fork-tender.

Taste the soup and adjust seasoning with additional salt and pepper as necessary.

Remove the bay leaf, ladle the soup into bowls, and garnish with chopped parsley before serving.