Cube eggplant into 1/2-inch cubes. Place cubes in a colander and sprinkle with about a teaspoon of salt. Put a bowl filled with water on top of the eggplant to press. Let sit for 30 minutes. Meanwhile, prep other ingredients.
You can cook orzo in advance. When done, rinse with cold water and toss orzo with a drizzle of olive oil to keep the pasta from sticking.
Preheat oven to 350 °F. When eggplant is done pressing, rinse with cold water. Heat 2-3 tablespoons of olive oil in a large skillet over medium-high heat. Once hot, add eggplant pieces and cook for 8-10 minutes until eggplant pieces are browned and lightly charred. Add herbs de provence and red pepper flakes to the eggplant and cook for another minute. Remove from the pan.
Add another drizzle of oil to the skillet. Add onions, carrots, celery, and red pepper and cook until veggies are softened. Add garlic and cook for another minute.
In a large bowl, stir together eggplant, veggies, orzo, tomatoes, and diced mozzarella. Season the mixture with a pinch of salt and pepper.
Transfer the mixture to a 2 1/2 quart (or 9×13) baking dish. Dust heavily with grated Parmesan cheese.
Bake for 20 minutes at 350 °F. covered with foil. Then uncover and bake for another 15-20 minutes.