Creating the French Baked Potato Meatball Casserole is a straightforward process if you follow these steps:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Make Meatballs: In a large bowl, combine ground beef or turkey, breadcrumbs, Parmesan cheese, egg, garlic powder, onion powder, salt, and pepper. Mix until well combined. Form into small meatballs, about one inch in diameter.
3. Brown Meatballs: In a skillet over medium heat, add a little oil and brown the meatballs on all sides. This should take about 5-7 minutes. Remove and set aside.
4. Prepare Potatoes: In a baking dish, layer half of the sliced potatoes at the bottom. Sprinkle with salt and pepper.
5. Add Meatballs: Place the browned meatballs evenly over the potatoes.
6. Layer Remaining Potatoes: Add the remaining potato slices on top of the meatballs. Season with salt and pepper.
7. Make Sauce: In a bowl, mix the cream of mushroom soup, milk, and thyme until smooth. Pour the mixture evenly over the layered casserole.
8. Add Cheese: Sprinkle shredded cheddar cheese generously over the top.
9. Bake: Cover the baking dish with aluminum foil and place it in the preheated oven. Bake for 45 minutes, then remove the foil and bake for an additional 15 minutes or until the cheese is bubbly and golden brown.
10. Garnish and Serve: Once baked, let the casserole cool for a few minutes before garnishing with fresh parsley.

These steps will guide you in creating this incredible casserole effortlessly.