Turn your Instant Pot on to sauté mode. Add in your butter. Once fully melted, add in your onions. Sauté for 3-5 minutes until onions are translucent.
Add your minced garlic to your onions for about 1 minute. Enough to release the flavor, but not to burn them (they are quick to burn).
Press cancel on your Instant Pot.
Add in your thyme, salt, pepper, broth, and chicken breasts.
Place the lid on your Instant Pot. Close the sealing valve. Pressure cook on high for 10 minutes. Once time is done, do a quick release by opening the pressure valve to release all the pressure.
Remove your cooked chicken breasts. Shred and then transfer back to your pot liner.
Turn your Instant Pot on to sauté mode.
In a separate small bowl, mix together your milk and corn starch to create a slurry.
Slowly stir your soup while slowly adding in your slurry.
Add in your carrots, and gnocchi. Allow them to cook for about 5 minutes or until done.
Add spinach and allow them to cook and wilt into the soup. This should take about 1 minute.