Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large mixing bowl, combine the ground beef, breadcrumbs, Parmesan cheese, egg, minced garlic, onion powder, salt, pepper, oregano, and parsley. Mix until just combined; do not overwork the meat.
Shape the mixture into meatballs, about 1 inch in diameter, and place them on the prepared baking sheet.
Bake the meatballs in the preheated oven for 20 minutes, or until they are browned and cooked through.
While the meatballs are baking, prepare the gravy. In a large skillet, heat the olive oil over medium heat. Add the chopped onion and sauté until soft and translucent, about 5 minutes.
Sprinkle the flour over the onions and stir to combine, cooking for an additional minute.
Gradually whisk in the beef broth and Worcestershire sauce, bringing the mixture to a simmer. Cook until the gravy thickens, about 5-7 minutes. Season with salt and pepper to taste.
Once the meatballs are done, carefully transfer them to the skillet with the gravy, gently stirring to coat them in the sauce. Let them simmer together for an additional 5 minutes.
Serve the meatballs and gravy warm on a serving platter, and enjoy over mashed potatoes or pasta if desired.