Preheat the oven to 350°F (175°C).
In a large skillet, heat the olive oil over medium heat. Add the diced onion and cook until translucent, about 4 minutes. Add the minced garlic and cook for an additional minute.
Add the ground beef to the skillet, breaking it apart with a spoon. Cook until browned and cooked through, about 5-7 minutes. Drain any excess fat.
In a large mixing bowl, combine the browned beef mixture, cream of mushroom soup, sour cream, salt, pepper, and paprika. Mix well.
In the bottom of a greased 9x13-inch baking dish, layer half of the sliced potatoes.
Spread half of the beef mixture over the potato layer.
Repeat the layers with the remaining potatoes and beef mixture.
Cover the baking dish tightly with aluminum foil and bake in the preheated oven for 45 minutes.
After 45 minutes, remove the foil and sprinkle the shredded cheddar cheese on top of the casserole. Return to the oven and bake uncovered for an additional 15 minutes, or until the cheese is melted and the potatoes are fork-tender.
Allow the casserole to cool for a few minutes before serving. Garnish with fresh parsley if desired.