Preheat the oven to 325°F.
Slice the eggplant lengthwise and then using a knife or spoon, scoop out the seeds, leaving about a half to three quarters of an inch of flesh with the skin, and set the removed flesh aside. Spray a large pan with oil and place the eggplant in cut side down. Place the pan in the oven and roast for about 20 minutes.
Place the olive oil in a large skillet over medium high heat. Add the garlic and pinenuts and cook, tossing frequently, for about 3 minutes.
Add the celery, red and green peppers and cook, tossing frequently.
Chop the retained eggplant seeds and flesh into 1/2 inch cubes, and place in the pan with the tomatoes, water, salt, pepper, oregano, basil and marjoram. Reduce the heat to medium and cover.
Cook covered for about 20 minutes, stirring occasionally, and then uncover. Continue cooking until there is very little liquid left.
Remove the eggplant from the oven and stuff with the tomato and eggplant mixture. Top with the sliced mozzarella and then return the pan to the oven. Cook until the cheese is melted, then serve.
