Preheat oven to 375°F; grease a 1-quart baking dish.
Squeeze spinach dry; chop artichokes.
Mix cream cheese, sour cream, mayonnaise, 3/4 cup mozzarella, 1/4 cup Parmesan, garlic, salt, pepper, and red pepper flakes; fold in spinach and artichokes. Taste and adjust.
Spread in dish; top with remaining cheese.
Bake 25–30 minutes until bubbly and golden.
Serve in a white ceramic dish with parsley and chips.
Notes
Squeeze spinach to avoid watery dip.
Store in the fridge for 3 days or freeze unbaked for 2 months.