Peel and dice the onion. Grate or finely dice the garlic. Slice the potatoes into ¼ inch thick slices. Dice the bell pepper.
Heat up the olive oil in a skillet or frying pan over medium heat. Add the ground beef, and cook for a few minutes until it's browned.
Add diced onion and garlic to the skillet, and sauté for another minute or two, until the onion is soft and translucent.
Transfer the beef and onions to the slow cooker, along with all seasoning, sliced potatoes, canned diced tomatoes, diced bell pepper and beef stock. Stir to combine everything evenly.
Cover the crockpot with a lid, and cook on HIGH for 3-4 hours, or on LOW for 6-8 hours. Make sure that the potatoes are soft enough to easily pierce with a fork before you continue.
Add a drained canned of kidney beans to the slow cooker, and stir to combine.
Then, top the casserole with shredded cheese. Cover with a lid, and cook on LOW for 10-15 minutes, or until the cheese has melted.
Serve the casserole immediately while it's warm.