1. Preheat your oven to 375 degrees F (190 degrees C).
2. In a large mixing bowl, gently combine the ground beef, chopped onion, breadcrumbs, milk, egg, salt, and pepper. Press this mixture into a 9×9 inch baking dish.
3. Bake uncovered for 15 minutes. Then, remove from the oven and drain any excess fat.
4. Meanwhile, place the potatoes in a large pot and cover with enough water to submerge. Bring to a boil over high heat and cook for 15 minutes until tender.
5. Drain the potatoes and add butter, milk, salt, and pepper. Mash until creamy and smooth.
6. Spread the mashed potatoes evenly over the partially cooked meatloaf. Top with shredded cheddar cheese.
7. Return to the oven and bake for an additional 15 minutes, the cheese is bubbling, and the mashed potatoes are slightly crispy on the edges.

Nutritional Breakdown

• Calories : A slice of meatloaf paired with a serving of mashed potatoes and cheese can range from 500 to 800 calories, depending on the ingredients and portion sizes.
• Protein : Ground beef and cheese provide a good protein source, with a serving offering approximately 25-35 grams.
• Carbohydrates : Primarily from the potatoes and breadcrumbs, a serving might contain 40-60 grams of carbohydrates.
• Fats : The cheese, ground beef, and butter in the mashed potatoes contribute to the fat content, which can vary widely but often sits in the 20-40 gram range per serving.