Step 1

If making the quicker version, mix together the melted butter, cornstarch, milk, heavy cream, spices, seasoning, and most of the cheeses and set aside. Then continue to step 5...or, start with step 2:

Step 2

In a saucepan, cook the butter and cornstarch for a minute until they form a paste.

Step 3

Add the warm milk and whisk until smooth and then keep cooking for a further 2-3 minutes, until thick.

Step 4

Quickly add in spices, seasoning, and most of the shredded cheese, mix and switch off the heat.

Step 5

Layer half the potato slices in the Instant Pot-ready dish and pour on half the cheese sauce.

Step 6

Then add the remaining potatoes and top with the remaining sauce and sprinkle on the rest of the cheese. Cover the dish with foil.

Step 7

Add 1 ½ cups (350ml) of water to the Instant Pot, place a trivet inside the insert, then set the potato dish on the trivet.

Step 8

Place the lid on the Instant pot, turn the valve to sealing, and set to manual pressure/high pressure for 25 minutes (you will need up to 35 minutes if you use thicker potato slices).

Step 9

When done, perform a quick pressure release, then remove from the Instant Pot, discard the foil and place the scalloped potatoes under the broiler for 3-5 minutes until the top is golden and crispy.

Step 10

Preheat oven to 350 degrees F / 180 degrees C and lightly oil a baking dish.

Step 11

Melt the butter in a small saucepan over medium heat and quickly add in the cornstarch and cook for up to a minute until it forms a smooth paste.

Step 12

Slowly add in the milk and whisk until smooth and no lumps remain.

Step 13

Keep whisking the milk until thickened, and quickly add in the nutmeg, paprika, peppers, salt, 1 ½ cups (190g) of cheddar, and 2 tablespoons of Parmesan, then switch off the heat.

Step 14

Layer half the potatoes slices in the prepared oven dish and pour on half the cheese sauce.

Step 15

Then add the remaining potatoes and top with the remaining cheese sauce and sprinkle on the rest of the cheeses.

Step 16

Cover the dish with foil and bake in the preheated oven for 1 hour.

Step 17

Then remove the foil and bake uncovered for a further 25 minutes until the potatoes are cooked through and the cheese is golden.