Place potato cubes into a large pot and cover with cold water.
Heat potatoes on high and bring to a boil.
Boil for about 15 -20 minutes or until potatoes are soft.
Drain water from potatoes.
Add butter, milk, salt, and pepper
Mash potatoes with a potato masher or electric beater.Meat Layer
While potatoes are cooking heat oil is a saute pan over medium heat.
Add onions and garlic and cook 1-2 minutes until soft.
Add in ground beef and cook until browned.
Add in Worcestershire sauce, ketchup, thyme, salt, pepper, and beef broth. Cook for 1-2 minutes.
Sprinkle with flour and stir until thickened.
Stir in mixed vegetables.Place meat layer into a medium sized baking dish. Place mashed potatoes on top of meat layer and cover evenly. Bake at 350 degrees F for 20 minutes. Top with cheese and bake for another 5 minutes or until cheese is melted.