Add the rinsed spinach to the instant pot, then place the frozen cubes of onion masala on top along with the spices.
Secure the lid, close the pressure valve and cook for 2 minutes at high pressure.
Naturally release pressure.
Remove the lid and use an immersion blender to puree the contents of the pot.
Stir in heavy cream if desired - you can use as much or as little as you'd like (this will also lighten the color and be more "restaurant style"). Or top with ghee instead.
Taste the palak and adjust salt to your preference.
You can stir the cubes of paneer directly into the palak on sauté mode until the paneer is warmed through OR you can take an extra step and pan-fry the paneer separately.