Heat butter and oil in a large pot over medium heat. Add onion, carrots, and celery; sauté for 4–5 minutes until golden at the edges and veggies are tender.
Add garlic and cook for 30 seconds until fragrant.
Sprinkle flour over the vegetables; stir for 1 minute to form a light roux.
Gradually whisk in chicken stock; bring to a gentle boil.
Add chicken pieces; reduce heat and simmer for 10 minutes until chicken is cooked through.
Stir in egg noodles; cook for 7 minutes until tender with a slight bite.
Remove 1 cup of hot broth and whisk into cream and milk; return to the pot and heat gently for 1–2 minutes without boiling.
Season with salt and pepper, ladle into bowls, and top with mini croutons.
Notes
Refrigerate leftovers within 2 hours and consume within 3 days.Add mini croutons only just before serving to maintain their crunch.To freeze, omit croutons and thaw overnight before gently reheating.