Preheat oven to 425°; coat a 2-quart casserole dish with nonstick spray.
Boil potatoes in a large pot of salted water over high heat until fork tender, 12-15 minutes; drain and set aside.
Combine cream cheese and buttermilk in a large bowl; blend well.
Stir in cheddar, chives, parsley, dill, and cayenne; season to taste with salt and pepper.
Stir hot potatoes into cream cheese mixture until coated; transfer to prepared baking dish.
Combine bread crumbs, Parmesan, parsley, and paprika in a small bowl; season with salt and pepper.
Sprinkle topping over potato salad.
Bake, uncovered, until potatoes are completely soft and topping is golden brown, 20-25 minutes.
*Per serving--461 calories, total fat 28 g (17 g sat), 36 g carb, 2 g fiber.