Melt the butter in a soup pot over medium heat, then add in the onion and celery. Sauté for 5 minutes.
Stir in the garlic and flour and cook, stirring often, for another 1-2 minutes to cook the raw flour taste out.
Whisk in the chicken broth until the flour has dissolved.
Add in the cream, potatoes, frozen mixed vegetables, and Italian seasoning. When the soup is almost boiling, reduce the heat and cover the pot with the lid slightly open. Let the soup simmer for 15 minutes (it should be simmering fairly gently). Stir the soup occasionally during this time to ensure nothing is sticking to the bottom of the pot.
Stir in the chicken. Cook for another 5 minutes or until the potatoes are soft. This is a fairly thick soup, so if you want to thin it out, simply add a splash more chicken broth.
Season with salt & pepper as needed (I am generous with both) and serve with biscuits if desired.
