Preheat oven to 350°F.
Mix mayonnaise, cream cheese, and garlic together until smooth and creamy.
Add ¾ of mozzarella cheese and all the Parmesan to the mixture and mix together.
Prepare rigatoni according to package instructions. Before draining add spinach to pot and stir until wilted. Pour into strainer to remove water and pour into large mixing bowl.
Add chicken and artichokes to bowl and mix together.
Add cream cheese mixture and mix together.
Put the contents of the bowl into a 9x13 baking dish. Sprinkle remaining mozzarella cheese on top.
Bake for 20-30 minutes at 350°F, until cheese is melted and bubbly.
Remove from oven and serve.