In a skillet, heat olive oil and brown the ground beef with chopped onion until the meat is no longer pink. Drain any excess fat.
Spray the crockpot lightly with cooking spray or use a liner for easy cleanup.
Layer the sliced potatoes at the bottom of the crockpot.
Spoon the cooked beef and onion mixture over the potatoes.
Add the drained green beans and diced tomatoes as the next layer.
Spread the cream of mushroom soup evenly over the top.
Cover and cook on low for 6 to 7 hours, or on high for 3 to 4 hours, until the potatoes are tender.
During the last 15 minutes of cooking, sprinkle shredded cheddar cheese over the top and let it melt.
Serve warm straight from the crockpot, and enjoy the cozy comfort in every bite.