Set oven to 375 degrees Fahrenheit (190 C).
Melt the butter and garlic oil (or minced garlic) together over medium heat in a big skillet.
When the spinach has thawed, add the artichoke hearts and spinach to the pan and cook for a few minutes.
Mix in the gruyere, white cheddar, 1 cup of parmesan, and cream cheese.
Add salt, nutmeg, mustard powder, black pepper, and red pepper flakes for flavoring. To blend, stir.
Transfer the prepared mixture to a baking dish that can go in the oven when it has melted and blended thoroughly. Sprinkle the remaining 1/2 cup of parmesan.
Bake for TWENTY to TWENTY FIVE minutes.