Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish with olive oil or butter.

In a large skillet over medium heat, cook the ground beef and chopped onion until browned, about 6-8 minutes. Then drain excess grease and stir in minced garlic and seasonings.

Peel the russet potatoes if desired and slice them thinly, approximately 1/8 inch thick.

In the greased baking dish, add a layer of sliced potatoes, then spoon half of the beef mixture and sprinkle half of the cheddar cheese on top. Repeat the layers.

Cover the dish with foil and bake for 60 minutes. Remove the foil and bake for another 15-20 minutes until the cheese is golden and bubbly.

Let the casserole cool for about 10 minutes before serving. Serve warm.