Meat and Potato Casserole

Alden's Grandmother's Meat and Potato Casserole
(All recipes are courtesy of Emeril Lagasse)
Ingredients
 1 pound fresh green beans, trimmed
 2 pounds russet potatoes, peeled and cubed
 1 tablespoon plus 1 teaspoon salt
 5 tablespoons unsalted butter
 1 tablespoon freshly ground black pepper
 3/4 cup whole milk
 1 tablespoon olive oil
 2 pounds ground beef
 2 cups chopped yellow onions
 1 cup chopped celery
 1 tablespoon minced garlic
 One 16-ounce can whole tomatoes, crushed with the juice
 2 cups shredded Cheddar cheese (optional)
Directions
 Preheat the oven to 350ºF.
 Bring a medium pot of water to a boil.
 Add the green beans and cook until tender, about 6 minutes.
 Drain the beans and put them in a large bowl filled with ice and water to cool.
 Drain again and reserve.
 Meanwhile, combine the potatoes and 1 teaspoon salt with water to cover in a medium saucepan over high heat and bring to a boil.
 Lower to a simmer and cook until tender, 20 to 25 minutes.
 Drain the potatoes and return to the pan.
 Add the butter, 1 teaspoon salt, 1 teaspoon black pepper, and 1/4 cup milk.
 Mash the potatoes until smooth but slightly lumpy and reserve.
 Heat the olive oil in a large heavy skillet over medium-high heat.
 Add the ground beef, season with the remaining 2 teaspoons salt and 2 teaspoons black pepper, and cook, stirring, until well browned, about 6 minutes.
 Add the onions and celery and cook, stirring, until the vegetables begin to soften, about 2 minutes.
 Add the garlic and cook until fragrant, about 30 seconds.
 Add the green beans and cook for 5 minutes, stirring occasionally.
 Add the tomatoes and cook, stirring, for 5 minutes.
 Add the remaining 1/2 cup milk and cook, stirring, for 4 minutes.
 Remove from the heat and reserve for later use.
 Spread half of the potatoes in the bottom of a 9 x 13-inch baking dish.
 Pour in the meat mixture, then top with the remaining mashed potatoes.
 Sprinkle with the cheese and bake until bubbly and golden brown, about 1 hour.
 Remove from the oven and serve hot.