Pro tip Once completed, click the steps to erase them.
Preheat grill to 350°F (175°C).
Sear chicken breasts 1–2 minutes on each side.
Turn off burners on one side of grill, then move chicken to that side to cook over indirect heat. Cook 15–20 minutes or until internal temperature reaches 165°F (75°C).
Meanwhile, thinly slice white mushrooms and onion.
Heat butter and oil in a saucepan.
Add mushrooms and sauté 5–6 minutes or until softened, season with salt and pepper, then keep warm.
Remove chicken from grill and let stand under foil for a few minutes.
Brown rolls on grill. Turn off grill and assemble burgers.
Spread mayonnaise on bread, then add lettuce, chicken, and cheese. Top with onions, mushrooms, and other half of roll.