Heat half the olive oil in a large saucepan over medium-high heat. Cook the eggplant, red onion, mushrooms and garlic for 8-10 minutes or until softened.
Meanwhile, heat the remaining olive oil in a large frying pan over medium-high heat. Saute the Roma tomatoes about 5 minutes or until juicy and tender. Transfer tomatoes to the saucepan.
Cook and stir the beef mince in the same frying pan for 5 minutes or until browned and crumbly. Transfer to the saucepan. Add the pasta sauce, tomato puree, diced tomatoes, sugar, spaghetti recipe base, salt and pepper. Simmer, stirring occasionally, about 15 minutes or until sauce is thick.