Preheat your oven to 350°F (175°C). Brown 1 pound of ground beef over medium heat, add 1 chopped onion and cook until beef is no longer pink and onion is translucent, about 7-10 minutes. Drain excess fat.

In a greased 9x13-inch baking dish, layer thinly sliced potatoes, followed by the beef and onion mixture.

In a mixing bowl, combine 1 can of cream of mushroom soup with 1 cup of milk, whisk until smooth, and pour over the layers.

Sprinkle 2 cups of shredded cheddar cheese on top and bake for 30 minutes, or until cheese is melted and bubbly.

Mix 1 cup of breadcrumbs with paprika and optional Parmesan cheese. After 30 minutes, remove the casserole and distribute the breadcrumb mixture on top.

Return to the oven and bake for an additional 15-20 minutes, until topping is golden brown and crispy.

Let cool for 5-10 minutes before slicing and serving.