Preheat your oven to 375°F (190°C) and grease a 9×13-inch baking dish to ensure your casserole doesn't stick.

Heat 2 tbsp of olive oil in a large skillet over medium heat. Sauté the diced onion until it turns translucent, about 3-4 minutes. Then, add the minced garlic and cook for another 30 seconds.

Stir in 4 cups of cauliflower rice and 2 cups of fresh baby spinach; sauté for about 3-5 minutes until the spinach wilts and the cauliflower softens slightly.

Add 1 cup of low-sodium chicken broth, 1 tsp of dried thyme, and season with salt and pepper. Simmer for another 5 minutes.

Transfer the mixture to the greased baking dish and top with 2 cups of shredded cheese. Spread it out evenly.

Bake for 25-30 minutes, or until bubbly and golden brown on top. Let it cool slightly before serving.