Cook the pasta: Bring a large pot of salted water to a boil.
Cook the pasta until just al dente, then drain and rinse under cool water to stop cooking. Toss with a teaspoon of olive oil if desired to prevent sticking.
Prep the chicken: If not using leftover or rotisserie chicken, grill or bake chicken breasts with salt, pepper, and a light drizzle of oil. Let cool, then chop or shred into bite-size pieces.
Mix the dressing: In a large bowl, whisk Greek yogurt, buffalo sauce, apple cider vinegar or lemon juice, garlic powder, and onion powder.
Taste and adjust heat by adding more buffalo sauce. Add a pinch of salt and pepper.
Add the mix-ins: Stir in the chopped celery, carrots, bell pepper, and green onions. Fold in the chicken until coated.
Combine with pasta: Add the cooled pasta to the bowl and gently toss until everything is evenly coated.
If the salad looks dry, add a splash more buffalo sauce or a spoonful of yogurt.
Finish and chill: Fold in fresh herbs and crumbled blue cheese or feta if using. Cover and chill for at least 20–30 minutes to let flavors mingle.
Season and serve: Give it a final toss. Adjust salt, pepper, or buffalo sauce to taste.
Garnish with extra green onions or herbs before serving.