1. Peel the potatoes and cut them into small pieces. Bring a pot of salted water to a boil and cook the potatoes for about 15-20 minutes, until they are tender.

2. Drain the cooked potatoes and return them to the pot. Add the milk and mash with a potato masher until creamy. Season with salt and pepper.

3. Season the hamburger patties with salt and pepper on both sides. Cook in a skillet or on the grill over medium heat until cooked through.

4. Split the hamburger buns in half and lightly toast them.

5. Place a slice of American cheese on the bottom half of each bun, then place the hamburger patty on top. Top with additional toppings like tomatoes, lettuce, and onions if desired.

6. Place the top half of the bun on top and serve the hamburger with creamy mashed potatoes.