Preheat oven to 400 degrees. Chop onion and sauté in a little olive oil. Season it with s & p. Meanwhile, wash tomatoes and slice off the top of the tomato and dig out the flesh and seeds of the tomato and put in a medium bowl. Place hallowed out tomatoes in a greased pan to bake in. Add the sliced kalamata olives, chopped zucchini, sautéed onion, and splash of olive oil to the tomato in the bowl. Season with a little s & p to your taste. Mix up with your clean hands and stuff each tomato so it is over flowing. Top with a little mozzarella and basil. Bake 25 min. Enjoy!