Put the cauliflower florets in a large bowl. Drizzle on the olive oil and toss to coat the cauliflower evenly.
In a small bowl, mix together half of the Ranch packet, the paprika, garlic powder, salt and pepper. Sprinkle the mixture over the cauliflower and toss to coat.
Add in the parmesan and toss to coat.
Roast in the oven for 25 minutes, then flip and continue cooking for 10 more minutes, until the cauliflower starts to get a little browned.
Mix the Greek yogurt with the remaining Ranch mix. Serve for dipping on the side.