In a saucepan over medium heat, sauté the onion in the olive oil until translucent and tender. Add sausages and cook for 5 minutes or until slightly browned, ensuring the sausage is broken into bite sized pieces. Add the mushrooms, basil and red wine. Cook until the wine reduces a bit, about 3 minutes. Add the tomatoes, let simmer for 8 minutes and then add milk, salt and pepper to taste. Remove from heat.
Bring a large pot of salted water to a boil and cook the rigatoni according to package directions. Drain and return the pasta to the pot. Add the sausage/tomato sauce and mix well with the pasta.
To serve, place pasta in individual heated serving bowls and sprinkle with cheese. Garnish with a basil leaf for a nice decorative touch. Serves 4-6.