To make the dressing, whisk together in a medium bowl, the mayonnaise, whole milk, white vinegar, ranch seasoning, granulated sugar, salt, and pepper. Transfer ½ cup of the dressing to a separate bowl to reserve. Set aside the dressing to thicken up while you make the rest of the recipe.
In a large mixing bowl, add the cooked and drained bowtie pasta and allow it to cool for 10 minutes while you dice all your other ingredients.
To the cooled bowtie pasta, add the remaining 1 cup of dressing and toss it to coat all the pasta with the dressing.
To the bowl of pasta and dressing, add the diced ham, diced cheddar-Monterey jack cheese, diced cucumber, diced red onion, and grape tomato halves.
Toss all the diced vegetables, diced ham, and diced cheese with the dressing-coated bowtie pasta until everything is evenly distributed.
Transfer to a large serving bowl, cover with plastic wrap, and refrigerate until ready to serve.