Preheat the oven to 450 degrees F (230 degrees C).
Cut eggplants in half, then cut each half into thirds, leaving 12 eggplant spears total. Place on a baking sheet and brush with 2 tablespoons olive oil.
Roast in the preheated oven until fork tender, 15 to 20 minutes. Reduce the oven temperature to 350 degrees F (175 degrees C).
While eggplants are cooking, heat remaining 2 tablespoons olive oil over medium heat in a medium to large pan. Add bell pepper, onion, and garlic to the hot pan and cook until onions become tender, 5 to 7 minutes. Stir in tomatoes and cook until most of the liquid has evaporated, 2 to 3 minutes. Set aside to cool.
Remove eggplants from the oven and let cool slightly, 5 to 10 minutes. Transfer eggplants to a 9x13-inch baking dish. Slice each spear vertically using a fork and knife, being careful not to cut through skin. Pry each open and fill with 2 to 3 tablespoons of tomato filling. Cover with tomato sauce.
Bake in the preheated oven until bubbling, about 30 minutes. Season with salt and pepper. Garnish with parsley.