Cook the rotini pasta until al dente in a pot of salted water. Drain, rinse with cold water, then cool to room temperature.
Chop the bacon strips into small pieces and fry them over medium-high heat until crispy. Place on paper towels to soak up the excess grease.
For the dressing, combine the mayonnaise, sour cream, ranch dip mix, and milk until smooth and well blended. Set aside.
In a large bowl, mix the cooked pasta, cheddar cheese cubes, green peas, diced tomatoes, and chopped bacon.
Add the dressing and gently toss until everything is well-coated. Cover with plastic wrap and refrigerate for at least 30 minutes before serving for optimal flavor. Enjoy!