Add sliced potatoes to the Instant Pot.
Add broth, salt, pepper, oregano, and garlic powder, stir to combine.
Close the lid, point valve to sealed and cook on High Pressure for 1 minute, followed by a 3 mins NPR and after that release manually the remaining pressure.
Preheat oven to 375 degrees F.
Gently transfer the potatoes from the IP to a pie baking dish and set aside.
Turn the Saute mode on, and add the garlic to the leftover liquid in the pot. Stir and cook for 30 seconds.
Add cream and let it slightly simmer. Turn off IP and add 1 cup of shredded cheese, stir until fully melted and smooth.
Pour the cheese sauce over the potatoes, toss to distribute and sprinkle on top the remaining 1 cup of shredded cheese.
Bake for 15 minutes, or until the mixture is bubbly. Broil for a few minutes to brown the top.