Melt 4 tablespoons of butter in your large stockpot over medium heat. Add the diced onion, carrots, and celery, stirring occasionally until the vegetables soften, about 5-7 minutes. Then, stir in the minced garlic and cook for another minute until fragrant.
Sprinkle in the dried thyme, parsley, and basil, stirring to combine. Next, gradually sprinkle the 1/3 cup of flour over the veggies, stirring constantly to create a roux. Cook this mixture for 2-3 minutes, which will help thicken the soup later and give it a lovely velvety texture.
Slowly whisk in the 8 cups of turkey broth, making sure to break up any lumps from the flour. Bring the mixture to a gentle boil, then reduce the heat and let it simmer for about 10 minutes, allowing the flavors to meld and the soup to thicken slightly.
Stir in the shredded turkey, evaporated milk, salt, and pepper. Simmer for another 5 minutes, stirring occasionally to make sure the soup is heated through and the seasoning is balanced.
Add the dried egg noodles to the pot, cooking according to package instructions, usually about 7-9 minutes, until tender but still firm to the bite. Stir occasionally to prevent the noodles from sticking together.
Finally, stir in the frozen peas and cook for an additional 2 minutes until warmed through. Taste and adjust the salt and pepper if needed. Ladle the Turkey Noodle Soup into bowls and enjoy the perfect harmony of creamy broth, hearty turkey, and tender noodles.