Preheat the grill to medium heat. Place a large pot of salted water over high heat and bring to a boil. Salt and pepper the chicken breasts.
Once the grill is hot, grill the chicken for 5-6 minutes per side. Then remove from heat and allow it to rest. Meanwhile, drop the pasta in the boiling water. Cook for 6-8 minutes, then drain and cool.
Place all the ingredients for the homemade Caesar dressing in the blender. Puree until smooth. Chop the chicken breasts into bite-size pieces and roughly chop the romaine lettuce.
To assemble, place the pasta, tomatoes, black olives, and chopped green onions in a large bowl. Top with the chopped grilled chicken Then pour the dressing over the pasta salad and toss to coat. If making ahead, cover the Chicken Caesar Pasta Salad and refrigerate until ready to serve.
Right before serving, toss in the chopped romaine, shredded Parmesan cheese, and croutons. Salt and pepper to taste. Serve cold or at room temperature.