Press the saute button on your Instant Pot, and when it reads HOT add the oil.
Add the sausage, onion, and seasonings to the pot and saute, stirring often, just until the sausage has begun to brown and the onions have softened- about 2 minutes. Press the cancel button to turn off the pot.
Add the broth and potatoes to the Instant Pot, then the lid- turning to close. Turn the vent valve to the sealed position, then press the manual/pressure cook button and set the time for 2 minutes.
When the timer beeps to let you know it's done cooking, CAREFULLY open the vent valve to let all the steam out in a quick release.
In a small bowl, whisk the milk and cornstarch together until evenly combined. Pour it into the pot, and press the saute button again.
Cook, stirring, for roughly 2 minutes to allow the sauce to thicken. Stir in the half & half until fully incorporated.
Serve & enjoy!