Preheat your oven to 400°F (200°C).
In a large bowl, toss the cauliflower florets with olive oil, garlic powder, Italian seasoning, salt, and black pepper until evenly coated.
Spread the seasoned cauliflower on a baking sheet in a single layer. Bake for 20 minutes, or until the cauliflower is tender and starting to brown.
Remove the baking sheet from the oven and pour the marinara sauce over the roasted cauliflower.
Sprinkle the mozzarella and Parmesan cheese evenly over the sauce.
Return the baking sheet to the oven and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let it cool for a few minutes. Garnish with fresh basil if desired before serving.