Start by bringing a large pot of salted water to a boil. Add the cauliflower and cook for about 5-7 minutes until tender. Drain and set aside.
In a skillet, heat 1 teaspoon of olive oil over medium heat. Add the onion and sauté for 3-4 minutes until translucent. Add the minced garlic and cook for another minute until fragrant.
In a large mixing bowl, combine the sautéed onion and garlic mixture with the cooked cauliflower, 1 cup of grated Parmesan cheese, Greek yogurt, milk, salt, smoked paprika, and pepper. Stir until well combined.
Fold in the fresh spinach until it wilts slightly from the heat of the mixture.
Preheat your oven to 375°F (190°C). Transfer the mixture to a baking dish and sprinkle the remaining 1/2 cup of Parmesan cheese on top. Drizzle with the remaining 1 teaspoon of olive oil. Bake for 20-25 minutes until bubbly and golden brown.
