Place the onions and butter in a large stockpot or Dutch oven over medium-high heat.
Fry the onions until soft, then add in the celery and carrots.
Fry for another 4-5 minutes, then add in the poultry seasoning.
Fry for 1 minute, then pour in the broth.
Bring to a low simmer and cook until the vegetables are tender.
Add in the turkey and the pasta and cook until the pasta is tender, around 10-11 minutes, stirring occasionally.
Remove from the stove top and serve hot. Store in a closed container in the fridge for 3-4 days or freeze for up to 3 months.
Notes
Precooking the pasta is an option. Cooking the pasta in the soup will add starches to it, which gives a heavier broth in the end, which we love so we always cook pasta in the soup broth. The choice is up to you.