Bring a large pot of salted water to a boil. Add the pasta and cook according to package instructions until al dente. Drain immediately and rinse under cold running water until the pasta is completely cooled. Drain thoroughly to ensure the dressing adheres properly.
While the pasta cooks, place the chopped turkey bacon in a medium skillet over medium heat. Sauté, stirring occasionally, until the bacon is crisp and golden brown, about 5 to 7 minutes. Transfer to a paper towel-lined plate to drain and cool.
In a medium mixing bowl, whisk together the mayonnaise, whole milk, white vinegar, salt, black pepper, and sugar until the dressing is smooth and creamy.
In a large salad bowl, combine the cooled pasta, crisped turkey bacon, halved grape tomatoes, sliced green onions, and cubed cheddar cheese.
Pour the dressing over the salad and toss gently with large spoons until all ingredients are evenly coated.
Fold in the fresh basil chiffonade just before serving to preserve its color and aroma.
For the best flavor, cover and refrigerate the pasta salad for at least 30 minutes before serving. Toss once more before plating.