Creating Amish Hamburger Steak Bake can be straightforward if you follow these simple steps:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Sauté Vegetables: In a skillet over medium heat, add the ground beef and chopped onion. Cook until the beef is browned and the onions are translucent. Drain excess grease.
3. Add Mushrooms: Stir in the sliced mushrooms and cook for about 3-4 minutes until soft.
4. Combine Ingredients: In a large mixing bowl, combine the cooked beef mixture, frozen mixed vegetables, cream of mushroom soup, beef broth, Worcestershire sauce, garlic powder, onion powder, salt, and black pepper. Stir until well combined.
5. Transfer to Baking Dish: Pour the beef mixture into a greased 9×13-inch baking dish, spreading it evenly.
6. Top with Mashed Potatoes: Spoon the prepared mashed potatoes evenly on top of the beef mixture. Smooth out the surface with a spatula.
7. Add Cheese: If desired, sprinkle shredded cheddar cheese on top of the mashed potatoes for added flavor.
8. Bake: Place the dish in the preheated oven and bake for 45-50 minutes or until heated through and golden on top.
9. Garnish: Remove from the oven and let it cool for a few minutes. Garnish with fresh parsley before serving.

These simple instructions will guide you in preparing an incredible meal that can easily be enjoyed anytime.