Peel and chop your russet potatoes into small cubes. Place them in the large pot carefully. Do not let them drop or crack. Cover them with two inches of cold water.

Drain the water from the potatoes. Add butter and milk to the pot. Mash them until they are very smooth and creamy.

Heat your skillet over medium heat. Add the ground beef and chopped onions. Cook until the meat is brown and fully done.

Stir in the garlic, carrots, and peas. Let them cook for a few minutes. This softens the vegetables and releases flavor.

Sprinkle the flour over the meat mixture. Stir it well for one minute. This helps the gravy thicken up later.

Pour in the beef broth and Worcestershire sauce. Let it simmer until the sauce is thick. This creates a rich and tasty filling.

Pour the meat mixture into your baking dish. Spread it out into an even layer. This is the base of your pie.

Spoon the mashed potatoes over the meat. Use a fork to smooth the top. You can make pretty patterns if you like.

Place the dish in the oven at 400 degrees. Bake for about twenty minutes. The top should be slightly golden brown.