PREPARE THE DISH:

Cup of Yum
1. Start by thinly slicing the potatoes using a mandoline slicer or sharp knife. 
2. In a medium size bowl, whisk the heavy cream, milk, garlic, flour, salt, pepper, red pepper flakes, and dry mustard. Set aside.
3. In a separate bowl, combine the gruyere, parmesan, and cheddar cheese. Set aside.
4. Using cooking spray, generously grease a 7x3-inch push pan that fits inside your pressure cooker. 
5. Layer half of the sliced potatoes into the bottom of the pan, followed by half of the cheese mixture. Pour half of the milk mixture over the top.
6. Repeat by adding the remaining potatoes then the remaining milk. Save the remaining cheese mixture for after pressure cooking.

PRESSURE COOK:

1. Pour 1 ½ cups of water into the bottom of your Instant Pot. Place your baking dish on a trivet and carefully lower into the pot.
2. Secure the lid in place and make sure the valve on top is set to SEALING.
3. Cook on high pressure for 40 minutes. After cook time ends, do a QUICK RELEASE of the pressure.
4. Carefully remove the pan by lifting the trivet, and top the potatoes with the remaining cheese. At this point you can either lower it back into the hot pressure cooker, and allow the cheese to naturally melt, or you can place the pan under the broiler so you get the bubbly cracked cheese.
5. To broil, turn broiler to high. Place baking dish under broiler until cheese is bubbly and begins to brown, about 3-5 minutes.
6. Allow potatoes to rest about 10 minutes before serving. Garnish with fresh parsley and extra crushed red pepper flakes, if desired.