In a skillet over medium heat, add olive oil. Once hot, add the ground beef and cook until browned, breaking it apart with a spatula., Add salt and pepper to taste, along with diced onion and garlic. Cook until the onion is translucent and fragrant., Wash the potatoes thoroughly, peel them, and slice them thinly for even cooking., Preheat the oven to 350°F (175°C)., Take a large baking dish and start layering. Begin with a layer of sliced potatoes, followed by a layer of the cooked ground beef mixture, then pour over some of the soup mixture., Continue layering until all ingredients are used, ending with a layer of potatoes on top. Pour any remaining soup mixture over the top layer., Finish by sprinkling the shredded cheddar cheese evenly over the casserole., Cover the baking dish with aluminum foil to prevent burning. Bake for 50 minutes., After 50 minutes, remove the foil and bake for an additional 20-30 minutes, or until the top is golden and the potatoes are tender., Allow the casserole to rest for 10-15 minutes before serving.