Cook the pasta: Bring a large pot of salted water to a boil. Cook pasta until just al dente according to package directions. Drain and rinse under cool water to stop cooking.
Shake off excess water well.
Blend the dressing: In a blender or food processor, combine cottage cheese, Greek yogurt, buffalo sauce, lemon juice, Dijon, garlic, onion powder, salt, and pepper. Blend until completely smooth and creamy. Taste and adjust heat and salt.
Prep the mix-ins: While the pasta cools, chop celery, shred carrots, and dice red onion.
If using chicken or other add-ins, have them ready.
Toss it together: In a large bowl, add cooled pasta, celery, carrots, red onion, and parsley. Pour over most of the dressing and toss until well coated.
Fold in cheese: Gently mix in crumbled blue cheese. If the salad looks dry, add the remaining dressing.
If it looks too saucy, add a bit more pasta or veggies.
Chill to set: Cover and refrigerate for at least 30 minutes to let flavors meld. It thickens as it chills.
Finish and serve: Before serving, taste and adjust seasoning. Add a splash more buffalo sauce for heat or a squeeze of lemon for brightness.
Garnish with extra parsley and a few blue cheese crumbles.