Place a large pot of salted water on the stovetop and bring to a boil. Cook the pasta according to package instructions. Drain the pasta in a colander and rinse with cold water to cool. Allow the pasta to drain while you prep the remaining ingredients.
Chop the sun dried tomatoes into bite-sized pieces. Place the mayonnaise, red wine vinegar, Italian seasoning, garlic, crushed red pepper, and 1/4 cup chopped sun dried tomatoes in the blender jar. Cover and puree.
Place the cooled pasta, chopped chicken, spinach, remaining chopped sun dried tomatoes, olives, and onions in a large salad bowl. Add the creamy dressing and toss to coat. Cover the bowl with plastic wrap and refrigerate until ready to serve.
NOTES: This pasta salad can be made up to 5 days ahead. You can use any variety of pitted olives you like.