Begin by preheating your oven to 375°F (190°C).
In a large mixing bowl (Bowl 1), toss the cauliflower florets with olive oil, salt, and black pepper. This step ensures every floret gets an even coat, which I found crucial for that golden, roasted flavor.
Transfer the seasoned cauliflower to a baking dish, spreading them out evenly.
In another bowl (Bowl 2), whisk together the heavy cream, minced garlic, half of the cheddar and parmesan cheese, thyme, rosemary, and red chili flakes if using. I once skipped the chili flakes, and while the dish was creamy and delicious, the mild heat does add a special touch.
Pour this creamy mixture over the cauliflower florets into the baking dish. Ensure each floret is nicely coated.
Sprinkle the remaining cheddar and parmesan cheese on top. It will give the casserole a delightful golden crust, a game-changer for me when I first tried it.
Place the baking dish in the preheated oven and bake for about 35-40 minutes, or until the cauliflower is tender and the top has a beautiful golden brown hue.
Once baked to perfection, please remove it from the oven and let it sit for a few minutes before serving. This patience, though challenging, ensures that the flavors meld together wonderfully.