01 - Boil rotini in generously salted water until al dente, then drain and rinse under cold running water to halt cooking. Spread on a sheet pan to cool completely.
02 - Whisk together mayonnaise, sour cream, and ranch seasoning in a large mixing bowl until smooth. Stir in 1 tablespoon of milk, adding more only if a thinner consistency is desired.
03 - Add the cooled pasta to the dressing and toss thoroughly until every piece is evenly coated.
04 - Gently fold in the halved cherry tomatoes, diced bell pepper, shredded cheddar, bacon bits, sliced green onions, and thawed peas, taking care not to crush the tomatoes.
05 - Taste the salad and add salt, pepper, or an extra pinch of ranch seasoning as needed to balance the flavors.
06 - Cover and refrigerate for at least 30 minutes to allow the dressing to permeate the pasta and the flavors to meld together.