Melt the butter in a large pot over medium heat. Add the onion and cook until it softens.
Stir in the flour and cook for one minute to form a roux.
Add the beef cubes and brown them on all sides.
Pour in the beef broth and stir to combine. Season with thyme, salt, and pepper.
Bring the mixture to a simmer, then cover and cook for 45 minutes.
Add the parsnips and continue simmering for 20 minutes until they begin to soften.
Stir in the apple and cook for another 15 minutes until the beef is tender and the broth has thickened.
Use a potato masher to lightly crush some of the parsnips directly in the pot for extra creaminess.