Turn the Instant Pot on saute mode. Add the cooking oil to the pot. When it gets hot, add the onions. Saute for 3 minutes.
Add the ground Italian sausage to the pot and break it up with a spatula while cooking. Saute until it’s cooked and browned, about 5 minutes.
Add the garlic and cook for 30 seconds. Turn off saute mode.
Add the seasoning and salt. Stir it into the sausage mixture.
Stir in the chicken stock and deglaze the bottom of the pan.
Layer the ravioli over the top in a single layer. Don’t stir.
Add the diced tomatoes evenly on top of the ravioli. Again, don’t stir.
Secure the lid and set the vent to sealing (if necessary for your model).
Set to cook on high pressure for 0 minutes (1 minute if the ravioli is frozen). When done, immediately release the pressure. Remove the lid and stir.
It will be a bit liquidy. That’s how it should be.
Add the spinach to the pot, stir, and allow to wilt for a few minutes. Then add the Parmesan cheese to the pot. Stir to combine.
Allow the ravioli to rest for 5 minutes before serving.