Step 1

Heat half of the oil in a deep ovenproof frying pan, or flameproof casserole dish, and fry the pork pieces over a medium high heat in batches until seared all over, then transfer to a plate. Add another 1 tbsp oil to the pan, if you need to, while you’re cooking the batches. Once all the pork is seared, transfer to a plate and set aside.

Step 2

Add another 1 tbsp oil to the pan with a little butter and fry half the leeks with a pinch of salt for 10 mins until tender. Add the garlic, fry for a minute, then stir in the flour.

Step 3

Pour in the cider, a little at a time, stirring to pick up any bits stuck to the bottom of the pan and to combine everything. Add the stock, bay leaves and seared pork, then simmer, half-covered with a lid for 1-1½ hrs until the meat is just tender (it will later cook to the point of falling apart in the oven). Can be prepared a day ahead.

Step 4

Heat the oven to 200C/180C fan/gas Simmer uncovered for a few minutes to reduce the sauce, if you need to – it shouldn’t be too liquid or the potatoes will sink into the sauce. Stir in the parsley, chopped sage, remaining leeks, and the cream, then season well.

Step 5

Peel both types of potatoes and cut into slices 2mm thick, by hand or using a mandoline. Alternate layers of potato and sweet potato in circles over the pie, or randomly, if you prefer. Dot the cubed butter over the top and bake for 1-1½ hrs until the potato is tender. Nestle in the whole sage leaves, brushed in a little oil, for the last 10 mins. Leave to rest for 10 mins before serving.