Preheat the oven to 400°F. Tear 4 sheets of heavy duty foil, 12 inches each, and lightly spray with non-stick cooking spray.
In a large mixing bowl, combine diced potatoes, sliced carrots, and sliced onions. Add olive oil.
Add 1/2 teaspoon salt, 1/2 teaspoon garlic powder, and 1/4 teaspoon black pepper. Mix well to coat vegetables.
Divide the ground beef into 4 equal portions and flatten into patties.
Sprinkle both sides of the patties with the remaining 1/2 teaspoon salt, 1/2 teaspoon garlic powder, and 1/4 teaspoon black pepper.
Divide the seasoned vegetables among the 4 sheets of foil, placing them in the middle.
Add a beef patty to the center of each pile of vegetables. Top each patty with a slice of butter.
Bring the edges of the foil together over the vegetables and fold twice to seal. Bring the short edges in to seal completely.
Place the foil packets on a baking sheet in a single layer.
Bake 30 to 35 minutes, or until vegetables are tender and beef is cooked through.
Carefully open packets and serve. Watch out for the hot steam!