Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a large mixing bowl, combine the ground beef, breadcrumbs, Parmesan cheese, parsley, egg, minced garlic, onion powder, salt, and black pepper. Mix until well combined, but do not overmix.
Shape the mixture into 16 meatballs and place them on the prepared baking sheet. Bake in the preheated oven for 20 minutes, or until cooked through.
While the meatballs bake, prepare the gravy. In a large skillet, heat the olive oil over medium heat. Whisk in the flour and cook for about 2 minutes until golden.
Gradually add the beef broth, whisking constantly to avoid lumps. Stir in the Worcestershire sauce and garlic powder. Bring the mixture to a simmer and let it thicken for about 5 minutes. Season with salt and pepper to taste.
For the cauliflower mash, steam the cauliflower florets until tender, about 10-12 minutes.
Transfer the steamed cauliflower to a food processor, add heavy cream, butter, salt, and pepper, and blend until smooth and creamy.
Once the meatballs are done, add them to the gravy and stir to coat.
To serve, spoon the creamy cauliflower mash onto plates and top with meatballs and gravy.