Preheat the oven to 425° then line a baking sheet with parchment paper for easy cleanup.
Cut the cauliflower head into florets then transfer to the baking sheet. Drizzle with olive oil, salt, pepper and garlic powder then gently toss to coat.
Roast cauliflower 15-18 minutes on a lower oven rack until tender-crisp and lightly brown on the bottom.
In a medium bowl, melt the butter then add sour cream, softened cream cheese, 1 cup of the cheddar and 1/2 cup of the gouda cheese.
Lightly spray a shallow casserole dish with cooking spray then add the roasted cauliflower. Add dollops of the cheese mixture to the top of the cauliflower then sprinkle with the remaining cheese and bake 8-10 minutes or until golden and bubbly.Garnish (optional) with fresh chopped parsley and serve warm.