Creating this delicious French Onion Pot Roast Casserole is simple if you follow these easy steps:

1. Preheat your oven to 325°F (163°C).
2. Sear the Pot Roast: In a large skillet, heat olive oil over medium-high heat. Season the pot roast with salt, pepper, and garlic powder. Sear the meat on all sides until browned, about 4-5 minutes per side. Remove the roast and set aside.
3. Caramelize the Onions: In the same skillet, add the sliced onions. Cook over medium heat, stirring frequently, until the onions are soft and caramelized, about 15-20 minutes.
4. Add Broth and Sauce: Once the onions are caramelized, add the beef broth, French onion soup, Worcestershire sauce, and dried thyme. Stir well to combine.
5. Combine Ingredients: In a large casserole dish, place the seared pot roast in the center. Pour the onion and broth mixture over the roast.
6. Cover and Bake: Cover the casserole dish tightly with aluminum foil. Bake in the preheated oven for 2 hours or until the roast is tender and easily pulls apart with a fork.
7. Add Cheese: Remove the casserole from the oven and carefully take off the foil. Sprinkle the Gruyère and mozzarella cheese evenly over the top.
8. Broil: Return the casserole to the oven and switch to broil. Broil for 3-5 minutes, or until the cheese is bubbly and golden brown. Keep a close eye to avoid burning.
9. Garnish: Remove from the oven and let it cool for a few minutes. Sprinkle with fresh parsley before serving.

Following these steps will help you create a delightful French Onion Pot Roast Casserole that is sure to impress!