Cut up your onions into small bits, and add them to a large skillet, with a tablespoon of oil or butter or fat, and fry on medium heat.
Add sliced mushrooms and some sprinkles of salt and with a spatula stir together until mushrooms and onions are soft. If you are adding chipotle or another ground pepper for kick, mix in now. Keep warm on burner.
On a baking sheet, or dish, lay out your tortillas and add mushroom mix, with spinach next and cheese on top. Don’t add too much cheese, especially around the edges, as it will all melt out. Place another tortilla on top and gently press down. Don’t crowd them on the sheet and use two pans if necessary.
Heat in oven for 6-8 minutes until cheese is melted and tortilla is slightly browned. Take out a let cool for a minute. Bring to the cutting board and slice into quarters.
Notes
If not consumed, refrigerate leftovers for up to 3 days.
Reheat in oven or toaster oven. Some even enjoy them cold!