Prep the Patties:
In a large bowl, mix ground beef with garlic powder, onion powder, salt, pepper, and thyme. Form into 4 patties.Brown the Patties:
Heat olive oil in a skillet over medium heat. Brown the patties 3–4 minutes per side. Remove and set aside.Make the Mushroom Gravy:
In the same skillet, sauté mushrooms until soft. Sprinkle with flour and stir to combine. Gradually whisk in milk and cook until thickened.Assemble the Bake:
Layer sliced potatoes and onions in a greased baking dish. Place the browned patties on top, then pour the mushroom gravy over everything.Bake:
Cover with foil and bake at 350°F (175°C) for 45 minutes. Remove foil, sprinkle cheddar over the top, and bake 10–15 minutes more until cheese is melted and bubbly.
