You know, I found a big shroom, cremini or bella, and seasoned it and grilled it like a burger for my MIL who was no longer eating beef.
Served it like a burger also.
Large Swiss brown is good done in a pan, or on a flat griddle.
Cook smooth side down. a bit of butter, seasoning, and Worcestershire sauce sprinkled on top, then drop some water on the hot pan, and cover the mushrooms with a bowl or lid.
I do them like this when I'm cooking on a gas BBQ (grill??)
Would work well as a burger substitute