Preheat oven to 450ºF. Place rack on lowest position in oven.
In a small bowl, mix together mayo, garlic, 1/4 cup feta cheese and oregano. Spread onto crust, leaving about an inch on the edges.
Sprinkle with tomatoes and olives. Bake for about 10 minutes.
Top with spinach, onion and 1/4 cup feta cheese. Return to oven and bake until onion and cheese is softened, about 2 minutes.
Cut into slices and serve. Enjoy!