Preheat the oven to 375°F (190°C).

Steam or boil the cauliflower until tender, about 10–15 minutes. Drain, mash, and set aside.

In a large mixing bowl, mix mashed cauliflower, garlic powder, onion powder, cream cheese, and half of the cheddar cheese until creamy.

Fold in the diced bell peppers and spinach into the cauliflower mixture.

Pour the mixture into a greased casserole dish, spreading evenly.

Sprinkle remaining cheddar cheese over the top.

Bake for 25-30 minutes until bubbly and golden brown.

Let cool for about 10 minutes before serving.