Step 1

Halve or quarter the potatoes so they’re all about the same size. Put in a large pan, add cold water to cover, salt well and bring to the boil. Simmer for 20 minutes until tender.

Step 2

Meanwhile, heat the oil in a frying pan over a low heat. Add the onion and leeks and fry for 10 minutes until soft. Add the bacon or pancetta and fry for 3-5 minutes until browned. Season to taste and set aside.

Step 3

Preheat the oven to 190°C/fan 170°C/gas Drain the potatoes well and mash coarsely, mixing in the butter and milk. Season well and add the egg. Stir to combine.

Step 4

Stir in the leek mixture, parsley, paprika and half the cheese, then use to fill a 24cm buttered casserole. Sprinkle over the remaining cheese and bake in the preheated oven for 35-45 minutes until well browned. Serve immediately.