For the Ranch dressing: Whisk together the Ranch dressing mix, milk, and mayonnaise. Chill at least 30 minutes in the fridge to thicken.
Cook the pasta according to the package directions. Drain and rinse with cold water to stop the cooking process.
In a large bowl, add the pasta, tomatoes, red onion, and pepper. Toss with the Ranch dressing, reserving 1/2 cup for later. Chill until ready to serve. Right before serving add the bacon, lettuce, and parsley tossing well. Add the remaining dressing if needed as the pasta will soak up the dressing.
I have tried this with both bottled and fresh Ranch dressing and fresh is 100% better. If you have a dressing you love, you can use it instead of making it from the mix.