Put the eggplant into a stockpot, and fill with water to cover. Bring the water to a boil over medium heat, and cook the eggplant until just tender, about 10 minutes. Drain, and set the eggplant aside to cool, taking care not to pierce the skins.
Preheat the oven to 350F. Line 2 baking pans with foil, and set aside.
Meanwhile, heat the oil in a large skillet over medium heat, and sauté the tomatoes and onion for 10 minutes, or until the onion is translucent. When the eggplants are cool enough to handle, carefully slice in half lengthwise, and scoop out the flesh. Chop the flesh finely, and add to the onion mixture in the skillet. Stir in the cheese, salt, pepper and cinnamon, mixing well and cooking for 2 to 3 minutes over medium heat, stirring constantly. Remove from the heat, and spoon and mound the eggplant mixture into the shells. Brush the tops of the filling with the egg yolks.
Bake the eggplants for 20 minutes, or until golden brown. Remove from the oven, and serve warm.