Preheat an oven to 350 degrees. Prepare two large mushroom caps by using a spoon to gently remove the stalk and most of the inner flesh. You can discard the shavings or include it in the filling made later. Rub the first amount of olive oil over the top of the mushroom caps and lay them in a oven safe baking dish.
Step 2
Prepare the filling by chopping the spinach, arugula, olives, and red bell pepper. Combine these ingredients in a bowl with the salt, pepper, chopped basil, oregano, and second amount of olive oil.
Step 3
Stuff both mushroom caps evenly with the filling. Top them both off with an even distribution of grated parmesan and chopped feta cheese.
Step 4
Cover the baking dish in tin foil and bake in the oven for 25 minutes. Then, uncover the dish and bake for an additional 10 minutes. Serve hot while the cheese is melted!