My Nanay and I loved the outcome!
2 portabella mushroom caps
amount of other ingredients will depend on how much you want to stuff your mushroom caps --
about 2 to 4 oz of crumbled feta cheese
sliced baby spinach
shredded mozarella cheese (to make the veggies stick together)
salt and pepper to taste
Assemble as shown. Bake in an oven toaster at 400 deg F for about 20-30 minutes or until veggies and mushroom caps are done (and cheese on top gets toasted). Sprinkle with salt and pepper to taste. Wait to cool down a bit before biting!