For the slow roasted tomatoes, place the tomato halves in rows cut-side up on a parchment-lined sheet pan. Drizzle with olive oil and sprinkle with salt and pepper. Roast the tomatoes for 2 – 2-1/2 hours until they are wrinkled and mostly dried except for a little juice in the center. (If not using immediately, store in the refrigerator up to 3 weeks.)
Cook the orzo until al dente following package instructions. Drain and set aside.
Preheat a grill pan over medium high heat. Toss the zucchini with 1 teaspoon olive oil, 1/4 teaspoon salt and 1/4 teaspoon pepper. Grill the zucchini on one side for 2 minutes until grill marks appear. Flip it and grill for an additional 2 minutes. Let the zucchini cool slightly and dice into 1/4-inch pieces.
In a large bowl combine the orzo with the tomatoes, zucchini, pesto, chives and remaining salt and pepper. Serve topped with grated Parmesan.
Serve warm, room temperature or cold. If served cold, it will likely require more salt and pepper to bring out the flavors of the dish.