Heat 1 tsp. olive oil in a skillet over medium-high heat. Add the diced zucchini, yellow squash, red onion, bell pepper and tomatoes, and season with salt and pepper. Saute for 5 minutes until cooked, then remove from heat.

Meanwhile, brush the tops of each pita bread with olive oil. Top with basil. Sprinkle the pita bread with the cooked zucchini, yellow squash, red onion, bell pepper and tomatoes. Cut the mozzarella balls in half and sprinkle on top of the other toppings. Bake at 400 degrees, or grill, until the pita is slightly crispy and the cheese is bubbly. Sprinkle with freshly grated Parmesan cheese, cut into wedges and serve.