Preheat oven to 425°F; line a rimmed baking sheet with parchment paper. Spread cauliflower in a single layer on baking sheet. Drizzle with olive oil, and sprinkle with 1/4 teaspoon salt and pepper. Bake 10 minutes, or until golden brown. Remove from oven, sprinkle with garlic powder, toss and bake 10 minutes longer.
Stir together hot pepper sauce and butter in a small bowl. Pour over cauliflower and toss.
For blue cheese dip, combine yogurt, green onion, blue cheese, mayonnaise and vinegar. Stir well. Serve with cauliflower.