Melt 3 Tablespoons of butter in skillet on medium heat
Add onions, sauté until tender - Add mushrooms and stir together and saute a few minutes longer
Move onions and mushrooms around making room to add each hamburger patty to the pan, salt and pepper each patty
Divide the the last Tablespoon of butter into quarters and top each patty with a piece, cover with the mushrooms and onions
Flip the burgers- giving 3-5 minutes on each side, depending on thickness of burgers, scatter mushrooms and onions on top
Whisk both packets of brown gravy with 2 cups of water in a bowl
Once burgers have cooked on each side, pour mixed gravy into the pan bring to a simmer, reduce heat and cook till burgers are cooked through.