Chop cheese into small chunks. Shredded cheese can be used if preferred.
Lay one soft taco shell on a heated pan or griddle set to medium heat. No oil or butter needed.
Place cheese on one side of soft taco shell.
OPTIONAL - add various cheese
OPTIONAL - add mushrooms
Fold over taco shell and press with spatula to make cheese "stick" the sides together.
Flip quesadilla. Don't wait too long or it will burn!
Cut quesadilla into thirds. I use a pizza cutter to make this task easier.
Put a tablespoon of sour cream on each quesadilla and sprinkle with chopped green onions (optional). Serve and enjoy!