Preheat oven to 400 degrees. Cut foil into (4) 12 x 18 inch pieces.
In a medium bowl mix ground beef and hamburger seasoning. (Use full mixture of 1/4 tsp of each seasoning above in ingredient list or 1 TBS of prepared hamburger seasoning blend.)
In another medium bowl mix diced potatoes, carrots, cooking oil and hamburger seasoning. (Use full mixture of 1/4 tsp of each seasoning above in ingredient list or 1 TBS of prepared hamburger seasoning blend.)
Place sheet of foil shiny side down. Place 1/4 of the vegetable mixture in center of foil. Top with 2 full slices of onion. Place 1 hamburger patty on top of onion. Top with 1 (pat) TBS butter.
Bring both long sides of foil together and roll down twice to seal. Flatten down each short edge of foil. Roll each flattened short edge of foil twice to seal.
Place packets on a sheet pan. Place in preheated oven for 35-45 minutes until vegetables are tender and hamburger is no longer pink. (Check at the 35 minute mark. Pull one packet out and open to verify it's done.
Pull packets out of oven and open them up carefully to avoid steam burn. Place 1 piece of cheese on each hamburger and place back in oven for 1-2 minutes to melt cheese.
Enjoy.