Preheat the oven to 350℉.
Combine the mozzarella cheese and parmesan cheese in a bowl. Set aside.
In a casserole dish or bowl, add the chopped artichoke hearts, spinach, softened cream cheese, sour cream, mayo, minced garlic, salt, pepper, and red pepper flakes.
With a spatula or spoon, mix until everything is well combined. (If mixing in a bowl, then transfer to the casserole dish.)
Spread the dip evenly in the casserole dish and top with shredded cheese, covering all the dip.
Bake at 350℉ for 20-25 minutes, until the spinach artichoke dip is bubbly and slightly golden.
Remove from the oven and let cool for 3-4 minutes and serve warm.
Enjoy with tortilla chips, crackers, bagel chips, etc.