Brown the ground beef in a large non stick pan, drain off excess fat then add to the slow cooker. Add the mixed vegetables, potatoes, and broth to the slow cooker, give it a quick stir then cover and set to Low for 5 hours or High for 2 1/2 hours.
Stir the soup, turn the setting to High, and slowly stir in the evaporated milk, garlic powder, salt and pepper as desired, then the cheese. Place lid back on the slow cooker.
Mix together the corn starch and the cold water until no lumps remain to make a slurry. When the cheese has melted in the soup, stir in the slurry, cover the slow cooker and keep on the High setting. Cook for another 20-30 minutes to thicken the soup a little.
Taste and adjust salt and pepper to your liking.
Ladle into bowls and serve. A salad or rolls on the side would make a perfect meal.