Creating the Amish Hamburger Steak Bake is straightforward if you follow these steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Cook Ground Beef: In a large skillet, brown the ground beef over medium heat until fully cooked. Drain any excess fat.
3. Add Vegetables: Stir in the chopped onion, bell pepper, and sliced mushrooms. Cook until tender, approximately 5 minutes.
4. Mix Ingredients: In a bowl, combine beef broth, cream of mushroom soup, Worcestershire sauce, garlic powder, onion powder, black pepper, and salt. Whisk until smooth.
5. Combine with Beef: Pour the mixture over the cooked beef and vegetables in the skillet. Stir well to combine everything evenly.
6. Add Frozen Vegetables: Gently fold in the frozen mixed vegetables into the beef mixture.
7. Transfer to Baking Dish: Pour the beef mixture into a greased 9×13-inch baking dish, spreading it out evenly.
8. Top with Mashed Potatoes: Spoon the prepared mashed potatoes over the beef mixture, spreading them to cover the top.
9. Add Cheese: Sprinkle the shredded cheddar cheese evenly over the mashed potatoes.
10. Bake: Place in the preheated oven and bake for 30-35 minutes, or until the cheese is melted and bubbly, and the edges are slightly golden brown.
11. Cool and Serve: Remove from the oven and let it cool for about 10-15 minutes before serving.

Following these steps will lead you to a delightful Amish Hamburger Steak Bake that will impress your family and friends alike.