Preheat the oven to 400°F (200°C). Slice the top off the garlic head, drizzle with 1 tablespoon olive oil, wrap in foil, and roast for 30–35 minutes until soft and caramelized. Cool slightly and squeeze cloves into a bowl.
Heat the remaining olive oil in a skillet over medium heat. Sauté the spinach for 2–3 minutes until wilted. Season with salt and pepper, then set aside.
Mash the roasted garlic until smooth. Add ricotta, half of the mozzarella, oregano, salt, and pepper, and mix well.
Spread the garlic-ricotta mixture evenly over the pizza crust. Top with spinach, remaining mozzarella, feta, and Parmesan. Sprinkle red pepper flakes if using.
Bake for 15–20 minutes until the crust is golden and the cheese is bubbly.
Cool slightly, garnish with fresh basil, slice, and serve. This Greek Roasted Garlic Spinach White Pizza is best enjoyed warm.