With the mushrooms, cut the stems down as close as possible to the mushroom top. (Photo is before being cut)
Oil the top of the mushrooms and sprinkle with salt and pepper. Place on a tray as depicted in the photo. Bake for 10-15 minutes @400 degrees or until golden brown.
Note: The mushrooms will develop a juice as the cook. This can make the sandwich messy. One option would be to cook directly on the rack and let it drip onto the tray.
While the mushroom tops are baking, grill your chicken. I have marinated mine in a bell pepper and spices sauce.
Prepare lettuce and tomatoes.
Once done baking, your mushrooms should have a beautiful brown color.
As mentioned before, you want to do your best to remove all the juice from the mushroom to make it less messy. I recommend poking holes and dabbing dry with a paper towel.
Assemble the sandwich and enjoy! The top of the mushrooms should be facing outward of the sandwich. Use toothpicks to help hold it all together. Serves great with sweet potato fries!