Start boiling a large pan of water, and add the potatoes when the water has come to a boil. The potatoes cook for about 20 minutes until soft.
Meanwhile, heat the olive oil in a large skillet on medium heat. Add the onions, and cook for 5 minutes, stirring occasionally. Add the carrots, cook for another 5 minutes.
Stir the ground beef into the skillet, stirring occasionally. After about 5 minutes, add the corn, peas, ketchup and soy sauce to the skillet. Stir to combine. Cook for another 5 minutes or so until the beef is about cooked through. Lower heat to keep warm as you mash the potatoes.
When the potatoes are soft, drain them and return the potatoes to the pan. Add the milk and butter, stirring and mashing the potatoes to combine them with the milk and butter. Add salt and pepper to taste. Set the potatoes aside for a moment.
Spread the beef mixture over the bottom of a large casserole dish. Use a large spoon to scoop the mashed potatoes on top of the beef, and use the back of the spoon to spread the potatoes evenly to cover the beef.
Bake the shepherd’s pie covered for 10 minutes, then remove the cover and bake for another 10 minutes. Put the oven onto a broil setting, and broil for a few minutes to brown the top of the pie.
Carefully remove the shepherd’s pie from the oven. Scoop out a serving, taking care to get beef mixture and potatoes. Plate the beef shepherd’s pie casserole and enjoy!