Heat the Instant Pot using the Saute function.
Add the chopped bacon and cook it, stirring frequently, until crisp, which will atake bout 5-8 minutes.
Remove the bacon with a slotted spoon, leaving behind the grease in the Instant Pot.
Add the onion and cook, while occasionally stirring, until the onions have started browning and they've softened. This will take about 5 minutes.
Add the kale and saute for another 2-3 minutes.
Toss in the garlic and cook for another minute.
Add in the potatoes, chicken stock, salt, and pepper. Stir them in gently.
Put on the lid and make sure that the valve is in the “sealing” position.
Set the Instant Pot to High Pressure Cook Manual mode for 7 minutes.
When it's done, do a quick release by switching the valve to the “venting” position. Remove the lid.
Gently stir in the heavy cream and butter.
Remove 2 tablespoons of liquid from the Instant Pot to a small bowl. Then whisk in the cornstarch until combined. Add the slurry to the soup.
Use an immersion blender to blend the soup to your desired consistency (if you like some texture, it's best to blend most of the soup, leaving some large chunks of potatoes). You can alternatively transfer the soup to a blender and blend in batches.
Cook on Saute-Low for another 5 minutes, or until the soup has thickened enough for your liking. Serve warm and garnish with bacon and cheese, if desired.
Refrigerate leftovers in an airtight container in the fridge for up to 3 days.