Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a mixing bowl, combine ground beef, breadcrumbs, Parmesan cheese, parsley, egg, garlic, salt, pepper, and onion powder. Mix until just combined.
Shape the mixture into meatballs, about 1.5 inches in diameter, and place them on the prepared baking sheet.
Bake the meatballs in the preheated oven for 20 minutes, or until cooked through (165°F or 74°C).
While the meatballs are baking, heat olive oil in a skillet over medium heat. Add chopped onion and sauté until translucent (about 5 minutes).
Pour in the beef broth, Worcestershire sauce, and soy sauce. Bring to a simmer.
If you prefer a thicker sauce, whisk the cornstarch and water mixture into the sauce and cook for an additional 2-3 minutes until thickened. Season with salt and pepper to taste.
Once the meatballs are cooked, add them to the sauce and simmer gently for another 5 minutes to absorb the flavors.
Serve the smothered meatballs over rice, pasta, or with a side of bread.