Cook the pasta right. Bring a large pot of salted water to a boil. Cook the pasta until just al dente according to package directions. You want it tender but still firm.
Rinse and cool. Drain the pasta, then rinse under cold water to stop cooking and chill the noodles.
Shake off excess water very well so the dressing doesn’t thin out.
Make the dressing. In a large bowl, whisk together mayonnaise, Greek yogurt, buttermilk, ranch seasoning, grated garlic, lemon juice, Dijon, black pepper, and a pinch of salt. Taste and adjust. It should be zesty, garlicky, and a touch tangy.
Prep the veggies and add-ins. Halve tomatoes, dice cucumber and bell pepper, chop red onion, and warm the corn to remove chill if using frozen.
Crumble bacon if using. Chop your herbs.
Toss gently. Add cooled pasta to the bowl with dressing. Fold in tomatoes, cucumber, bell pepper, red onion, corn, bacon, cheese, and most of the herbs.
Stir until everything is evenly coated.
Chill for best flavor. Cover and refrigerate for at least 30–60 minutes. The dressing will absorb into the pasta and the flavors will meld.
Finish and serve. Stir in a splash of buttermilk or water if the salad tightened up in the fridge. Top with remaining herbs.
Taste again for salt, pepper, and lemon before serving.