Preheat oven to 375 F. Grease a 9x13 baking pan or 2.5-quart casserole dish. Set aside.
Heat butter in a large pan over medium heat. Add garlic and stir in arrowroot powder. Slowly whisk in heavy cream and continue whisking until bubbly and thickened.
Stir in Italian seasoning, paprika, salt, black pepper, cream cheese and 1/4 of cheddar cheese and whisk until thickened and smooth.
Stir in broth and cauliflower rice followed by broccoli and spinach, then toss to coat. Add more cheese or cream as needed for desired consistency.
Pour into a greased 9x13 baking pan or 2.5-quart casserole dish.
Sprinkle with remaining shredded cheeses and bake for 37-42 minutes or until heated through and the top is lightly golden.
Serve hot and sprinkle with chopped parsley if desired.