Turn the instant pot onto the saute mode. Once hot, add the butter.
Once the butter is melted, add the onion and saute for about 5 minutes or until translucent. Add the garlic and poultry seasoning and saute for another minute.
Add in the potatoes, chicken breast, broth, salt, and pepper
Place the lid on and pressure cook on high for 10 minutes. Allow to natural release for 5 minutes, then manually release.
Take 1 cup of the potatoes and place into a blender along with 1 cup of broth. Add the cashews to the blender and blend on high for about 1 minute or until completely smooth. If should be thick and creamy with no chunks.
Turn the saute mode back on and add the potato cashew mixture back into the pot and stir. Add the frozen peas and carrots and stir again.
Bring to a simmer. Taste and add more salt if needed and enjoy!