Creating Beef-Stuffed Mushrooms is straightforward if you follow these simple steps:

1. Preheat Oven: Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
2. Clean Mushrooms: Gently wipe the mushrooms with a damp cloth to remove any dirt. Remove the stems and set the caps aside.
3. Prepare Filling: In a skillet over medium heat, add olive oil and sauté the chopped onions until translucent. Add minced garlic and cook for another minute.
4. Cook Beef: Add the ground beef to the skillet, breaking it apart with a spoon. Cook until browned and fully cooked through. Drain excess fat if necessary.
5. Mix Ingredients: In a large bowl, combine the cooked beef mixture with breadcrumbs, Parmesan cheese, mozzarella cheese, Worcestershire sauce, parsley, Italian seasoning, salt, and pepper. Mix until well combined.
6. Stuff Mushrooms: Spoon the beef mixture into each mushroom cap, pressing down slightly to pack in the filling.
7. Arrange on Baking Sheet: Place the stuffed mushrooms on the prepared baking sheet. Drizzle with a little olive oil.
8. Bake: Bake in the preheated oven for about 20-25 minutes, or until the mushrooms are tender and the tops are golden brown.
9. Serve Warm: Remove from the oven and let cool for a few minutes before serving.

These steps will guide you in creating this incredible dish effortlessly.