Preheat the oven to 350 degrees F (175 degrees C).
Slice the mushrooms, tomatoes and chop the spinach. Spread tomato pesto onto one side of each pita and place them pesto-side up on a baking sheet. Top pitas with tomatoes, spinach, mushrooms, feta cheese, and Parmesan cheese, then drizzle with olive oil and season with fresh ground pepper.
Bake in the preheated oven until pita breads are crispy, usually about 12 minutes. Cut pitas into quarters to eat like a pizza.
