In this order place the following in the cooker: minced garlic, heavy whipping cream, frozen spinach, chopped artichoke, cream cheese, cut butter, pepper and salt. DO NOT STIR.
Place the lid on set to Pressure cook on high for 4 minutes and do a quick release (be careful when releasing the pressure from the cooker). Follow the manufacture instructions for how to do a quick release. Remove lid.
Add ½ cup grated Parmesan cheese to the cooker and mix well.
In increments of two: add ½ cup shredded Parmesan cheese and mix well, repeat with the rest of the cheese.
In increments of two: add ½ cup shredded mozzarella cheese and mix well, repeat with the rest of the cheese.
Press the cancel button. Transfer the dip to a serving bowl and wait for 3-4 minutes before serving (it will thicken as it cools).