Preheat your oven to 375°F (190°C). Gather all your ingredients.

In a large mixing bowl, combine the cooked cauliflower, spinach, cream cheese, eggs, garlic powder, and onion. Mix until creamy.

Grease a casserole dish and pour the vegetable mixture into it, spreading evenly.

Sprinkle a layer of cheddar cheese and optional breadcrumbs on top.

Bake in the preheated oven for 30-35 minutes until bubbly and golden brown.

Allow to cool for 5-10 minutes before slicing.