Preheat oven to 180 degrees C. Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain.
Heat oil in a large, deep frypan. Place sausage and onion in the frypan and cook over medium high heat until evenly brown. Drain excess fat. Pour in wine, and cook for 1 minute, stirring, to deglaze the pan. Stir in tomato puree, diced tomatoes and tomato paste. Simmer for 10 minutes, stirring occasionally. Toss with cooked pasta, and place in a 20x30cm baking dish. Sprinkle top with mozzarella.
Bake in preheated oven for 20 minutes or until cheese is melted.