Add the frozen spinach, sour cream, cream cheese, water, salt, garlic powder, paprika, and red pepper flakes to the Instant Pot.
Attach the lid and ensure the valve is in the “sealing” position.
Set the timer for 5 minutes.
When the Instant Pot has finished cooking, release the pressure manually by switching the valve to the “venting” position-- be careful, it will steam and may splatter!
When the Instant Pot has depressurized, remove the lid. Switch the Instant Pot to the Saute-Normal function. Stir the mixture together— it will look curdled at first, that’s totally normal! Just keep stirring until you get a uniform mixture, about 1 minute.
Next, stir in the parmesan and mozzarella. Cook until the mixture starts to bubble and has thickened slightly, about 2 minutes.
This recipe can be made up to an hour in advance and kept warm using the “keep warm” setting on the Instant Pot.
Garnish with additional parmesan, if desired. Serve with crackers, chips, toasted baguette, or crudite.