For the cream sauce
30 g / 1 oz butter
1 + 1/2 cups cooking cream (about 300 ml)
2 cloves garlic, finely diced
2 anchovies, finely diced (optional)
1/4 teaspoon salt
1/4 teaspoon white pepper (black is fine as well)
For the leeks and potatoes
1 teaspoon butter
1 + 1/2 leeks (we used 1 large and 1/2 medium), washed and sliced thinly
8–9 medium white potatoes, peeled and sliced thinly
1 + 1/2 teaspoons salt
1 + ¼ cup (250ml) vegetable stock
2 cups grated cheese such as Cheddar or Greyer (or both)
Prepare all the ingredients before you begin. Combine the cream sauce ingredients in a bowl, whisk and set aside. Make sure the potatoes are sliced very thinly and evenly.
Turn the Instant Pot on and press the Sauté function key. Heat a teaspoon of butter in the inner pot and add one-third of the leeks. Spread them on the bottom and sprinkle with about ¼ teaspoon of salt.
Add a third of the sliced potatoes and spread over the leeks. Sprinkle with another pinch of salt (about 1/4 teaspoon). Pour over a third of the cream sauce evenly.
Add another layer of leeks and potatoes (another third of each). Sprinkle potatoes with another 1/4 teaspoon of salt. Pour another third of the cream sauce evenly.
Finish with the final layer of leeks and potatoes, a bit of salt and the final bit of the cream sauce.
Finally, evenly and gently pour over the vegetable stock. Use your hands to press down the potatoes and leeks so that the sauce comes up to the surface. They won’t be completely covered but we just want to apply some pressure so everything is nice and tight. Potatoes will give out some juice as well, which will incorporate into the dish. Press Cancel to stop the Sauté process.
Cover the Instant Pot with the lid, lock it and make sure the venting valve is pointing at Sealing. Set to Manual, 12 minutes, HIGH pressure. After 3 beeps the pressure will start to build and the cooking will commence. Once the timer goes off, allow about 10-15 minutes for the pressure to release naturally. Then use quick release method to let off the rest of the steam and open the lid.
While the Instant Pot is cooking, preheat the oven to about 220 C/ 420 F (unless you want to finish the dish at a later stage).
Transfer the potato and leeks mixture into a large casserole dish. Instead of using a spoon, which will break up the potatoes, simply tilt the inner pot over the baking dish, allowing the mixture to ‘slide into’ it, so to speak. Pour over all the remaining sauce and bits over the top. You can see some of the more browned leeks from the bottom of the Instant Pot.
Sprinkle with cheese and pop in the hot oven under the grill for 12 minutes, or until the cheese is melted and turned golden.