Step 1: Preheat the Oven and Prep the Dish

• Preheat your oven to 375°F (190°C).
• Grease a casserole dish with butter or non-stick spray to prevent sticking.

Step 2: Brown the Ground Beef

• In a large skillet, cook 1 lb of ground beef over medium heat until fully browned, breaking it apart with a spatula.
• Once cooked, drain any excess fat to avoid a greasy casserole. Set the beef aside.

Step 3: Prepare the Potato Layer

• Slice the baby potatoes thinly (¼-inch slices) to ensure they cook evenly.
• Layer the potato slices in the bottom of the greased casserole dish, arranging them evenly.
• Season with salt and pepper to taste for extra flavor.

Step 4: Add the Meat and Vegetables

• Spread the browned ground beef over the potato layer.
• Evenly distribute the diced onions and diced bell peppers over the meat layer.

Step 5: Pour the Mushroom Soup

• Open the can of cream of mushroom soup and pour it over the meat and vegetables.
• Use a spoon to spread the soup evenly to cover the entire layer, ensuring the flavors distribute well during baking.

Step 6: Top with Cheeses

• Sprinkle 1 cup of shredded cheddar cheese and 1 cup of mozzarella cheese over the casserole.
• Make sure the cheese covers the surface completely to achieve a bubbly, golden brown top when baked.

Step 7: Bake the Casserole

• Cover the casserole dish with aluminum foil to lock in moisture while it cooks.
• Bake in the preheated oven for 45 minutes to allow the potatoes to soften and the flavors to meld.

Step 8: Finish Baking Uncovered

• After 45 minutes, remove the foil and bake for an additional 15 minutes.
• This step allows the cheese to melt and develop a golden brown, bubbly top.

Step 9: Cool and Serve

• Let the casserole rest for 5-10 minutes before serving to allow the layers to set and make it easier to slice.
• Serve warm and enjoy this hearty, comforting dish!