Follow these steps to create mouthwatering meatballs and gravy:

1. Preheat Oven: Preheat your oven to 400°F (200°C).
2. Make the Meatball Mixture: In a large bowl, combine ground beef, breadcrumbs, Parmesan cheese, egg, garlic powder, onion powder, parsley, salt, and pepper. Mix until well combined.
3. Form the Meatballs: Shape the mixture into meatballs about 1 inch in diameter and place them on a baking sheet.
4. Bake the Meatballs: Put the meatballs in the preheated oven and bake for about 15-20 minutes, or until cooked through and browned.
5. Prepare the Gravy: While the meatballs are baking, heat olive oil in a large skillet over medium heat. Add sliced mushrooms if using and sauté for 3-4 minutes.
6. Add Broth: Pour in the beef broth and Worcestershire sauce. Bring to a simmer.
7. Thicken the Gravy: If desired, mix cornstarch with a little water to create a slurry and add it to the gravy. Stir until thickened.
8. Add Heavy Cream: Slowly stir in heavy cream for a richer flavor. Adjust seasoning if necessary.
9. Combine Meatballs with Gravy: Once the meatballs are cooked, add them to the gravy in the skillet, ensuring they are well coated.
10. Simmer Together: Let the meatballs simmer in the gravy for about 5 minutes to absorb the flavors.

With these steps, you’ll have perfectly crafted meatballs in a luxurious gravy, ready to be served.