Cook the Ground Beef: In a large skillet, cook the ground beef over medium heat until browned. Add the chopped onion, minced garlic, and diced red bell pepper. Cook until the vegetables are soft. Drain excess grease if necessary.
Layer the Ingredients in the Slow Cooker: Lightly grease the slow cooker. Begin by layering half of the potato chunks at the bottom. Add half of the cooked ground beef mixture over the potatoes. Repeat the layers with the remaining potatoes and beef mixture.
Mix the Cream Sauce: In a small bowl, whisk together the condensed cream of mushroom soup, milk, salt, black pepper, and paprika. Pour the mixture evenly over the layers in the slow cooker.
Cook Low and Slow: Cover the slow cooker with the lid and cook on low for 6-7 hours or on high for 3-4 hours, until the potatoes are tender.
Add the Cheese: About 15 minutes before serving, sprinkle the shredded cheddar cheese over the casserole. Cover the slow cooker and let the cheese melt.
Garnish and Serve: Once the cheese has melted, garnish the casserole with freshly chopped parsley. Serve warm and enjoy the hearty, comforting flavors!