Preheat your oven to 375°F (190°C) and grease a 9x13-inch casserole dish.

Brown 1 pound of ground beef for 7-10 minutes in a skillet over medium heat, then add diced onion, bell pepper, and minced garlic, cooking for an additional 5 minutes until soft.

In a mixing bowl, combine one can of cream of mushroom soup with 1 cup of sour cream and season with salt and pepper.

Peel and thinly slice Russet potatoes, layering half in the greased casserole dish and seasoning lightly with salt and pepper.

Spread the browned ground beef mixture over the potatoes, then pour the creamy mixture on top, followed by the remaining potato slices and shredded cheddar cheese.

Bake in the preheated oven for 30-35 minutes until potatoes are tender and top is golden brown.

Remove from oven, sprinkle French fried onions on top, and return to oven for an additional 5 minutes until crispy.

Let cool for a few minutes before serving, optionally garnishing with chopped parsley or green onions.