Bring a large pot of water to boil and cook your pasta according to package directions. Drain and rinse the pasta with cold water when done.
Meanwhile; saute chicken breasts in a pan over medium-high heat, seasoned with salt and pepper, flipping after about 5 minutes. Cook until internal temperature of the chicken reaches 165 degrees. Allow to rest for 10 minutes before dicing.
In a medium bowl (or mason jar), combine sour cream, mayonnaise, milk, ranch dressing mix and garlic powder. Stir together till smooth. Set aside.
In a large bowl, combine cooked pasta, chicken, diced tomato, cheese cubes, green onions, olives and bacon. Stir together to combine.
Cover and place in the fridge for 2 hours (or more) before serving.