Set your Instant Pot on “SAUTE” and melt the butter.
Add diced onions, celery, carrots, garlic, and chicken; add seasonings, salt and pepper, and continue to cook for about 4 to 5 minutes, or until chicken is browned and veggies are just beginning to soften.
Stir in chicken broth and tortellini; close the lid and lock it.
Set the steam release to “SEALING”.
Press “MANUAL” and adjust the time to 5 minutes.
When the cycle is finished, wait 10 minutes and then manually release the pressure.
Remove lid and press “SAUTE” again.
Stir in the spinach and half & half; cook for 1 to 2 minutes, or until soup is heated through.
Taste for seasonings and adjust accordingly.
Ladle into soup bowls and serve.