Creating Easy Shepherd’s Pie Casserole involves straightforward steps that anyone can follow. Here’s how to make it:

1. Preheat the Oven: Set your oven to 400°F (200°C).
2. Brown the Meat: In a skillet over medium heat, add the ground beef or lamb. Cook until browned, breaking it apart with a spoon.
3. Add Vegetables and Seasoning: Stir in the diced onions, minced garlic, and frozen mixed vegetables. Cook until the onions are soft.
4. Mix in Flavor: Add the tomato paste, Worcestershire sauce, dried thyme, salt, and pepper. Stir to combine everything well and let it simmer for a few minutes.
5. Prepare the Casserole Dish: Transfer the meat mixture to a 9×13 inch baking dish, spreading it evenly across the bottom.
6. Add the Mashed Potatoes: Spoon the prepared mashed potatoes on top of the meat mixture. Spread them out evenly to cover the filling completely.
7. Sprinkle Cheese: If desired, top the mashed potatoes with shredded cheddar cheese for an extra cheesy layer.
8. Bake: Place in the preheated oven and bake for 30-35 minutes or until the top is golden and the filling is bubbling.
9. Garnish and Serve: Once done, remove from the oven and let it cool for a few minutes. Garnish with fresh parsley before serving.

With these clear steps, you’re ready to enjoy the incredible flavors of Easy Shepherd’s Pie Casserole!