1. Preheat oven to 350 degrees Fahrenheit. Cut eggplant in half lengthwise. Using a knife, cut along the edges, forming a border. Score little half-inch cubes in the middle of the eggplant. With a spoon, dig out eggplant cubes so that you have an empty shell.
2. Place the half shells face down on a baking sheet. Bake for 10 minutes.
3. Heat oil in a sauté pan over medium heat. Add onions and sauté for five minutes. Add eggplant cubes, zucchini, and peppers. Sauté for 20 minutes or until soft. Season with salt, garlic, black pepper, and paprika.
4. Fill eggplant halves with vegetables. Sprinkle cheese and a squirt of ketchup. Bake for 15–20 minutes, or until cheese is melted.