Creating delicious meatballs and gravy is straightforward with these easy-to-follow steps:

1. Preheat the Oven: Preheat your oven to 400°F (200°C).

2. Prepare the Meatball Mixture: In a large bowl, combine ground beef, breadcrumbs, Parmesan cheese, parsley, egg, minced garlic, salt, pepper, and Worcestershire sauce. Mix until just combined.

3. Form Meatballs: Roll the mixture into meatballs about 1-2 inches in diameter. Place them on a baking sheet lined with parchment paper.

4. Bake Meatballs: Bake in the preheated oven for 20-25 minutes, or until browned and cooked through.

5. Make the Gravy: While the meatballs are baking, heat olive oil in a large skillet over medium heat. Add chopped onions and cook until translucent. If using, add the sliced mushrooms and sauté until tender.

6. Add Broth: Pour in the beef broth and bring to a simmer. Taste and adjust seasoning if needed.

7. Thicken the Gravy (Optional): If you prefer a thicker gravy, mix cornstarch with a little cold water to create a slurry. Stir it into the simmering gravy, letting it cook for a few more minutes until thickened.

8. Add Meatballs to Gravy: Once the meatballs are done baking, transfer them straight into the skillet with the gravy. Let them simmer for 5-10 minutes to absorb the flavors.

9. Garnish: If desired, sprinkle fresh herbs on top before serving.