Preheat the oven to 375°F (190°C). Slice the eggplants in half lengthwise and scoop out a portion of the flesh, leaving about 1/2 inch of the shell. Set the flesh aside in a bowl.
Brush the insides of the eggplant halves with olive oil and sprinkle with salt. Place them cut-side down on a baking sheet. Roast in the preheated oven for 20-25 minutes, or until tender.
While the eggplants are roasting, dice the reserved eggplant flesh into small pieces. Heat the remaining olive oil in a skillet over medium heat. Add the diced flesh, bell pepper, and zucchini. Sauté for about 5-7 minutes until softened.
Stir in the cherry tomatoes, kalamata olives, cooked quinoa, chopped parsley, oregano, and red pepper flakes (if using). Cook for an additional 2-3 minutes until everything is well combined and heated through. Season with salt and pepper to taste.
Remove the roasted eggplant halves from the oven and flip them over. Spoon the quinoa mixture into each half, pressing down gently to pack the filling.
Sprinkle the top with crumbled feta cheese. Return the stuffed eggplants to the oven and bake for another 10-15 minutes until the feta is slightly golden and the eggplants are heated through.
Carefully remove from the oven and let cool for a few minutes before serving.
Notes
Serve the stuffed eggplants on a platter, drizzled with a bit of olive oil and sprinkled with additional fresh parsley for a vibrant touch.