Start by bringing a large pot of salted water to a boil. Add the cauliflower florets and cook for about 5-7 minutes, or until they are tender but still firm. Drain the cauliflower and set aside.
In a saucepan over medium heat, combine the heavy cream, milk, minced garlic, and nutmeg. Stir until warmed through. Gradually whisk in the crumbled goat cheese until melted and smooth. Season with salt and pepper to taste.
In a large mixing bowl, gently fold the cooked cauliflower into the cheese sauce, ensuring each piece is well-coated. Pour the mixture into the prepared baking dish.
In a small bowl, combine the grated Parmesan cheese and breadcrumbs (if using). Sprinkle this mixture evenly over the cauliflower and cheese mixture. Drizzle with olive oil to help achieve that golden crust.
Preheat your oven to 375°F (190°C). Bake the gratin for 25-30 minutes, or until the top is bubbly and golden brown.
Let the gratin sit for a few minutes before serving. This allows it to set slightly, making it easier to scoop and serve.
