Cut eggplants in half, then cut each half into thirds to make 12 eggplant spears. Place on a baking sheet; 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; cook until onion becomes tender, 5 to 7 minutes. Stir in tomatoes; cook until most of the liquid has evaporated, 2 to 3 minutes. Set aside to cool.

Remove eggplants from the oven; 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 the skin. Pry each pocket open; fill with 2 to 3 tablespoons of the tomato filling. Cover with tomato sauce.

Bake in the preheated oven until bubbling, about 30 minutes. Season with salt and black pepper. Garnish with parsley.