Place chicken broth and minced garlic cloves in the Instant Pot.
Drain the artichokes in a colander and add them to the chicken broth mixture.
Add in the frozen spinach, sour cream, cream cheese, mayonnaise and onion powder in the Instant Pot.
Pressure Cook/Manual on High Pressure for 4 minutes.
Once the cooking time expires, quick release the pressure.
Remove the lid and stir in the Parmesan and mozzarella cheese until melted.
Transfer to a serving bowl and let cool 5-10 minutes. The mixture will thicken as it cools.