Pour boiling water to cover over mushrooms; let stand 15 minutes. Drain mushrooms, reserving 1/3 cup liquid; coarsely chop mushrooms. Set mushrooms and liquid aside.
Cook ground beef in a large skillet over medium heat until browned, stirring until it crumbles. Drain and set aside.
Saute onion, carrot, celery, and garlic in hot olive oil in a large skillet over medium-high heat until tender. Stir in reserved mushrooms, mushroom liquid, ground beef, pureed tomato, sun-dried tomato, and pepperoni; bring to a boil. Reduce heat, and simmer, uncovered, 35 minutes. Stir in whipping cream, basil, and pepper. Simmer, uncovered, 5 minutes or until slightly thickened. Stir in 1/2 cup Parmesan cheese. Serve over cooked spaghetti. Sprinkle with remaining 2 tablespoons Parmesan cheese.