3 pounds Yukon Gold potatoes, peeled and quartered
1 medium yellow onion, chopped
2 medium cloves garlic, minced
2 medium carrots, peeled and sliced
8 ounces frozen peas
1 1/2 cup shredded cheddar cheese, divided; 1/2 cup for potatoes, 1 cup for top
1/2 cup beef broth
1/2 cup milk
4 tablespoons butter, divided; 2 tablespoons for beef, 2 tablespoons for potatoes
2 tablespoons all-purpose flour
2 tablespoons Italian seasoning
1 teaspoon salt, divided; 1/2 teaspoon for potatoes, 1/2 teaspoon for beef
1/2 teaspoon pepper
Preheat oven to 350°F. Boil potatoes in a large pot until fork tender. Drain. Add milk, 2 tablespoons butter and 1/2 teaspoon salt. Smash until smooth. Add cheese and stir to combine. Transfer half of potatoes to bottom of 11-inch by 9-inch aluminum pan or casserole dish. Sauté ground beef, seasoned with salt and pepper, until cooked through. Transfer beef to plate lined with paper towel to drain. In the same skillet, sauté carrots and onions over medium heat until softened. Add ground beef and stir to combine. Add butter, peas, garlic, Italian seasoning, pepper and reserved salt, and cook until garlic is light brown, about 3 minutes. Dust with flour and stir to incorporate. Pour in beef broth and stir until thickened. Spoon beef mixture on top of potatoes and cover with reserved potatoes. Top with reserved cheese and bake until bubbling and browned, about 30 minutes.