Begin by bringing a large pot of water to a rolling boil. Add the tri-color rotini pasta and cook for about 8 minutes or until al dente. Drain and rinse under cold water.

In a mixing bowl, combine mayonnaise, sour cream, dry ranch dressing mix, garlic powder, and milk. Whisk until smooth and well-blended.

Add the cooled rotini pasta to the dressing. Incorporate cooked bacon, diced tomato, drained black olives, and shredded cheddar cheese. Fold together gently.

Cover the bowl and refrigerate for at least 2 hours to allow flavors to meld.

Stir gently before serving. Add a splash of milk if the salad seems dry. Garnish with additional bacon or cheese if desired.