Peel and chop the parsnips. Put in a pot and cover with water. Boil for about 15 minutes until fork tender.
Strain the parsnips and mash until smooth.
Stir in butter, salt and pepper.
Preheat your oven to 350.
Add avocado oil to a skillet on medium high heat. Brown the beef and set aside.
Add the other tablespoon of avocado oil on medium high heat and cook the onions, celery and carrots until onions are transparent. Add in the garlic to cook a minute or two longer.
Add in the frozen green beans and cook until thawed.
Stir in the remaining ingredients along with the beef.
Simmer for the mixture to thicken.
Transfer the beef mixture to a casserole dish and top with the parsnip mash.
Bake in the oven for about 30 minutes until the parsnips are golden on the edges.
Cool for 10 minutes before serving.