Hit SAUTE on the Instant Pot, and when it reads Hot, add the butter and onions, and cook until onions are slightly soft
Add the ground sausage, breaking it up as it cooks, and cook until no longer pink
Stir in the sea salt, garlic powder, Italian seasoning, black pepper and red pepper flakes if using, and hit CANCEL to turn pot off
Deglaze the bottom of the pot if necessary, with a little of the chicken broth, then add the potatoes and chicken broth to the pot
Place lid on pot, make sure vent is on Sealing position, and hit PRESSURE COOK or Manuel for 5 minutes. Hit START if your pot has this feature
Pot will take a few minutes to reach pressure, then begin cooking and counting down as it cooks. When pot beeps, allow a 5 minute natural release, then quick release remaining pressure. If pot starts to release liquid, do a gradual quick release
When pin drops, carefully remove lid, and stir soup. Stir in the chopped Kale, then stir in the heavy cream, and keep stirring until well combined and kale is soft
Serve topped with the bacon and grated Parmesan cheese and additional red pepper flakes if desired