I really wanted to taste the pasta itself, so I just served it with a little butter, some olive oil, and grated Parmesan.
Pasta with roasted cauliflower is one of my very favorite dishes. The key is to cut the cauliflower up into small pieces and to roast it, (drizzled with salt and olive oil), for a long time at a low temperature. You really want lots of caramelization which equals lots of flavor. To serve, I just mix the cauliflower with the cooked pasta--it's so delicious you really don't need to add anything else.