2 1/2 pounds russet potatoes - peeled and cut into 1/2 to 1-inch pieces
1 medium onion - thinly sliced
1 packet dry onion soup mix
1/4 teaspoon dried thyme
1 cup beef broth
1/2 cup butter - melted
1 cup shredded Swiss cheese
1 cup shredded mozzarella cheese
Chopped fresh parsley - optional
Preheat your oven to 375°F. Grease a 9×13-inch baking dish with cooking spray.
In a large mixing bowl, combine the potatoes, onion, dry onion soup mix, thyme, beef broth, and melted butter. Stir well to coat evenly.
Transfer the mixture into the prepared baking dish.
Cover the dish with foil and bake for 30 minutes.
Remove the foil and bake uncovered for an additional 30 minutes, stirring halfway through to ensure even cooking.
Sprinkle the shredded Swiss and mozzarella cheeses over the top and return the dish to the oven. Bake for an additional 5 minutes, or until the cheese is melted and bubbly.
Garnish with chopped fresh parsley, if desired, and serve hot.