Preheat oven to 350F.
Pat the meat very dry with paper towel. Preheat a Dutch oven or oven-safe pot over medium heat for 5 minutes. Add the avocado oil and heat it until shimmering. Raise the heat to medium-high and add the beef. Cook, undisturbed at first, until the beef develops a golden brown crust. Flip the pieces over and cook until browned on all sides, around 12 minutes total. Transfer the browned beef to a bowl and set aside.
Discard all but 2 tablespoons of rendered fat in the pot. Add the onion, celery, carrot and parsnips. Season with a pinch of salt and cook, stirring occasionally, until slightly softened, around 4 minutes. Add the mushrooms and cook, stirring occasionally, until slightly softened, around 4 minutes. Add the garlic, paprika and smoked paprika, and Magic Mushroom Powder and cook, stirring, for 60 seconds.
Add the beef broth and use a wooden spoon to lift any browned bits on the bottom of the pot. Return the browned beef to the pot. Tie the thyme and rosemary together with butcher's twine and add it to the pot along with the bay leaves and potatoes. Raise the heat to high, bring the liquid to a boil, and season with another pinch of salt and black pepper to taste. Cover the pot with a lid, transfer to the oven and cook until the meat is fork-tender, around 1.5 hours. If the meat is still tough after 1.5 hours, return the pot to the oven and cook an additional 30 minutes, then check again.
Discard the thyme, rosemary and bay leaves. Taste the stew for seasoning and adjust with salt and pepper as desired. If the stew is too thick, add some more beef broth to lengthen it. If the stew is too loose, simmer it over a medium heat until it thickens to your desired consistency.
Ladle the beef stew into individual serving bowls and garnish with parsley before enjoying.