Pasta Marinara with Chicken and Mushroom

4 boneless, skinless chicken breasts, cut into pieces
8 oz rotini, cooked and drained
4 cloves garlic, minced
2 cups sliced mushrooms
15 oz jar or container your favorite red pasta sauce
1 tomato, skinned and chopped
1/4 cup grated parmesan

Heat a little oil over medium heat. Add chicken and cook 3 minutes.
Add garlic and mushrooms and saute, stirring, about 3 minutes.
Add spaghetti sauce. Simmer 5 minutes or until chicken is heated through. Stir in tomatoes.
Serve chicken mixture over pasta. Sprinkle with parmesan.