Step 1: Preheat the Oven: Preheat your oven to 350°F (175°C).
Step 2: Prepare the Hamburger Steaks: In a large mixing bowl, combine the ground beef, chopped onion, minced garlic, breadcrumbs, egg, milk, salt, black pepper, and Worcestershire sauce. Mix until well combined, being careful not to overmix. Form the mixture into 4-5 oval patties.
Step 3: Sear the Patties: In a large skillet, heat the vegetable oil over medium-high heat. Sear the hamburger steaks for 2-3 minutes per side, until browned. Transfer the patties to a 9×13-inch baking dish.
Step 4: Make the Gravy: In the same skillet, melt the butter over medium heat. Stir in the flour and cook for 1-2 minutes to create a roux. Gradually whisk in the beef broth until smooth. Add Worcestershire sauce, dried thyme, salt, and black pepper. Bring the gravy to a simmer and cook for 3-4 minutes, or until thickened.
Step 5: Bake: Pour the gravy over the hamburger steaks in the baking dish. Cover the dish with foil and bake in the preheated oven for 30-35 minutes, or until the hamburger steaks are cooked through and tender.
Step 6: Serve: Serve the Amish Hamburger Steak Bake hot, with plenty of gravy spooned over each steak.