Bring a large pot of salted water to a rolling boil over high heat. Add the tri-color rotini pasta and cook it for about 8 minutes until it reaches an al dente texture. Once done, drain the pasta in a colander and rinse it under cold water to stop the cooking process.

In a large mixing bowl, whisk together the mayonnaise, sour cream, dry ranch dressing mix, garlic powder, and milk until the mixture is smooth. Ensure it's thoroughly blended and free of lumps.

Once the pasta is cool, gently fold it into the prepared dressing. Add the crispy cooked bacon, diced tomato, sliced black olives, and shredded cheddar cheese. Mix until evenly distributed.

Cover the bowl with plastic wrap and place it in the refrigerator. Let it chill for at least 2 hours to allow flavors to meld.