Saute garlic and onions in 2 tablespoons olive oil in a large frying pan until opaque, add diced tomatoes. Simmer covered on medium-low heat for 15-20 minutes until tomatoes are soft, but not completely broken down. While the tomatoes are simmering, boil the penne pasta to al dente. Slice grilled chicken into bite-sized pieces and add to pan of cooked tomatoes, onions and garlic. Stir to coat chicken. In a large serving bowl, add pasta and coat with 1-2 tablespoons of olive oil. Add tomato sauce and chicken to the bowl of pasta. Top with freshly grated Parmesan and sliced basil. Lightly toss, then salt and pepper to taste. Serve with garlic bread and garden salad.
Adapted from “Holly’s Pasta”, from Julia Williams