In a large pot over medium heat, melt the butter.
Add the onion, celery, and carrots. Cook, stirring occasionally, until the vegetables soften, about 5 minutes.
Stir in the thyme, salt, and pepper. Add the garlic and cook for 1 minute.
Sprinkle the flour over the vegetables. Stir until everything is coated and cook for 1 minute to remove any raw flour taste.
Push the vegetables to the edges of the pot. Add the chicken pieces to the center and cook for 3 to 4 minutes, stirring occasionally, until the outside of the chicken is no longer pink.
Slowly pour in the chicken broth while stirring to dissolve the roux. Increase the heat to high and bring to a boil.
Reduce to low and simmer for 15 minutes.
Add the egg noodles. Store bought noodles cook about 8 minutes. Homemade noodles cook about 3 minutes.
Stir in the heavy cream and let the soup simmer for 2 to 3 minutes until slightly thickened.