Christmas Ham, Leeks and Mustard Lasagne

In my household, we have two food-related traditions for Christmas. The first is that there has to be a ham, which I normally boil for a good 2 hours in cider and spices. I then slice it and we have it cold on bread with cheese and pickle throughout the holidays. Also, the choice par excellence for Christmas Eve is salmon. I buy a whole side from the fishmonger (about £25), slather it in honey, spices, mustard and citrus juice, then roast it until it’s just cooked and tender. Normally these are the two dishes which would accompany our holidays right until the end. However, not all things are eternal and even the ham is not going to last forever. What can you do, then, to make those leftovers go the extra mile?

Rather than throwing them away, I use them again in recipes. I would usually cook pasta and make a sauce with the leftover salmon and crème fraîche. The ham is very versatile and can be used in a wide variety of dishes, the lasagna suggested here being just one of them. You could also transform it into cannelloni, filled pasta shells, or ditch the pasta altogether and opt for a salad or a mousse. The amount of ham indicated below is purely an indication – use as much as you like. Also, make sure you wash the leeks after you sliced them as they tend to contain quite a lot of dirt and you don’t want to feel the grittiness under your teeth.



  • 1L whole milk
  • 100g + 50g unsalted butter
  • 100g plain flour
  • 2 tsp mustard powder
  • 2 tbsp Dijon mustard
  • approximately 700g cooked gammon joint
  • 2 large leeks, halved and finely sliced
  • approximately dried 10 lasagna sheets
  • 300g extra mature cheddar, coarsely grated
  • salt and pepper


  1. Start by making the bechamel sauce. In a large saucepan, gently melt 100g butter. Once that’s all melted, take the pan off the heat and add the flour. Use a wooden spoon to combine the mixture, which will look very messy but that is fine. Transfer the saucepan back onto a medium heat and cook the mixture for about 3 minutes, stirring constantly. Make sure the flour and butter mixture does not stick to the bottom of the saucepan.
  2. Meanwhile, warm the milk in another saucepan. Bring it to the boil, then turn off the heat. Slowly pour about a third of the warm milk into the egg and flour mixture, then mix with the wooden spoon to dissolve all of the flour. The mixture will thicken quickly since there is not much liquid. Slowly add another third of the milk and mix again to dissolve any lumps which might form. Finally, when the mixture is smooth again, pour in the remaining milk. If the mixture turns very lumpy, you can use a whisk to energetically mix it all together. Cook over a medium heat, stirring constantly, for a good 5-10 minutes, until the mixture has thickened and easily covers the back of the wooden spoon.
  3. In the meantime, melt the 50g butter with a drizzle of olive oil in another saucepan and add the sliced and washed leeks. Cook over a medium heat for approximately 10 minutes, until the vegetables have cooked down and are translucent. Remove the pan from the heat.
  4. Finely dice the cooked gammon, then add them to the pan with the leeks. Dollop in the Dijon mustard and season generously with salt and pepper. Season the bechamel sauce too and whisk in the mustard powder. Pour the bechamel sauce in the pan with the ham and leeks, then mix to combine.
  5. Pre-heat the oven to 180C.
  6. Start to assemble the lasagna by pouring a couple of ladlefuls of the bechamel mixture onto a deep baking tray (mine is 30x25cm). Spread the mixture to cover the bottom of the tray, then cover with the lasagna sheets, which you might have to trim to cover the whole surface. Now dollop about a third of the bechamel mixture onto the dried lasagna sheets, then sprinkle about a third of the grated cheese on top. Cover with more lasagna sheets, then repeat this process until you have run out of bechamel mixture and the top layer has been sprinkled with the cheese. Bake in the oven for 30 minutes until the lasagna is a lovely golden brown on top and the sauce is bubbling away. Remove from the oven and allow to sit for a good 10-15 minutes before serving, then cut it into portions and enjoy!




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