There are different variations of this recipe out there. The difference between a cottage pie and a shepard's pie, is the meat. Shepard's pie uses lamb. Also, some recipes call for sliced potatoes in place of the mashed. This is how our family prepares it. Enjoy!
Place diced potatoes in a medium saucepan. Cover with water and place over high heat. Allow to come to a boil. Boil for 15 minutes, or until potatoes are tender. Drain water. Mash potatoes until smooth, then add your butter, followed by milk. Whip until fluffy. Add salt and pepper to taste.
Brown your ground beef in skillet over medium heat and saute for one minute. Cook through until meat is no longer pink and onions are tender. Drain your grease from the pan.
Mix together your ketchup, garlic powder, and Worcestershire sauce. Add this to your skillet. Add salt & pepper to season. Simmer over low heat for about 10 minutes.
Spoon your beef mixture into a 9" pie pan. Followed by a layer of corn. And then spread a layer of your mashed potatoes. Lastly, add a generous amount of cheddar cheese to the top.
Bake for about 15 to 20 minutes. Or, until top is browned and your cheese starts to bubble.