Step 1: Preheat the Oven
1. Preheat Oven: Preheat your oven to 350°F (175°C).

Step 2: Cook the Ground Beef
1. Brown the Beef: In a large skillet over medium heat, add the ground beef and cook until browned. If using lean beef, add olive oil to prevent sticking.
2. Add Onion and Garlic: Add the diced onion and minced garlic to the skillet. Cook until the onion is translucent, about 3–5 minutes. Drain excess fat if necessary.
3. Season: Stir in salt, pepper, and paprika (if using).

Step 3: Assemble the Casserole
1. Layer Ingredients: In a greased 9×13-inch baking dish, layer half of the sliced potatoes on the bottom.
2. Add Beef Mixture: Spread the cooked ground beef mixture evenly over the potatoes.
3. Add Vegetables: Layer the mixed vegetables on top of the beef.
4. Top with Remaining Potatoes: Add the remaining sliced potatoes on top.
5. Add Soup: Pour the cream of mushroom soup over the entire casserole, spreading it evenly. You can add a little water or milk to the soup can, shake it, and pour it over the top for more moisture.
6. Cheese Layer: Sprinkle the shredded cheese over the top.

Step 4: Bake the Casserole
1. Cover and Bake: Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.
2. Uncover and Continue Baking: After 30 minutes, remove the foil and bake for an additional 15–20 minutes, or until the potatoes are tender and the cheese is bubbly and golden.

Step 5: Serve
1. Cool Slightly: Let the casserole cool for a few minutes before serving.
2. Enjoy: Serve warm and enjoy this hearty meal!