In a large bowl, gently toss together cooked chicken, tomatoes, and mozzarella.
Meanwhile, cook pasta according to package directions. Drain and rinse with cold water and set aside until pasta is completely cool.
Add cool pasta to bowl and stir to combine with chicken and other ingredients. Stir in ¼ cup pesto. Add additional pesto until all ingredients are well coated. Add salt and pepper, to taste.
Cover and refrigerate until ready to serve.
Just before serving, stir in pine nuts.