To cook a Christmas ham, simmer the gammon joint for 20 minutes per 450g plus an extra 20 minutes, then peel off the skin, score the fat, brush on a glaze and roast at 200°C fan (220°C/gas 7) for 20 to 25 minutes until sticky and golden. That is the whole method. The only thing most guides leave out is the part that actually matters on the day: how to cook it ahead and serve it cold, so the oven is free for the turkey and you carve the ham at your leisure.
The short version
- Gammon or ham? Raw, the cured joint is gammon; once cooked it becomes ham. You buy gammon and serve ham.
- Method: simmer, then glaze and roast. Simmering keeps it moist; the hot oven lacquers the glaze.
- Time: simmer 20 minutes per 450g plus 20 minutes, then 20–25 minutes to glaze.
- Glaze: honey and mustard is the classic. Brush it on only for the roasting stage, or the sugar burns.
- Get ahead: cook and glaze up to two days before and serve cold — the calmest way to feed a crowd at Christmas.
Gammon or ham? The one thing to know first
They are the same cut at different stages. Gammon is the raw, cured leg you buy from the butcher or supermarket; once you have cooked it, it is ham. So a recipe for “how to cook a gammon joint” and one for “Christmas ham” are the same job. You will also choose between smoked (deeper, smoky flavour) and unsmoked, sometimes called green (milder, lets the glaze lead). Both are correct; pick by taste.
Foolproof Glazed Christmas Ham
Serves 8–10 from a 2kg joint · prep 15 minutes · simmer about 1 hour 50 minutes · glaze-roast 25 minutes
You need
- 1 unsmoked or smoked gammon joint (about 2kg), boneless
- 1 onion, halved; 2 bay leaves; 1 teaspoon black peppercorns (for the simmering water)
- About 20 whole cloves, to stud
- Honey-mustard glaze: 3 tablespoons runny honey, 2 tablespoons English mustard, 2 tablespoons demerara sugar
Method
- Sit the gammon in a large pan with the onion, bay and peppercorns and cover with cold water. Bring to the boil, skim off any foam, then lower to a gentle simmer.
- Simmer, covered, for 20 minutes per 450g plus an extra 20 minutes (about 1 hour 50 minutes for a 2kg joint), topping up with boiling water so it stays submerged.
- Lift out and let it cool enough to handle. Heat the oven to 200°C fan (220°C conventional, gas mark 7) and line a roasting tin with foil.
- Slice off the skin, leaving an even layer of fat behind. Score the fat into diamonds and press a clove into the corners.
- Mix the glaze and brush half of it over the fat. Roast for 20–25 minutes, brushing on the rest halfway, until deep golden and sticky. Watch it: honey catches quickly.
- Rest for 15 minutes before carving. The centre should reach 70°C, held for a couple of minutes, on a probe.
Simmering keeps the meat moist; the short, hot roast at the end is what lacquers the glaze.
Gammon cooking times, by joint weight
Weigh the joint cold and work from that. The simmer does the cooking; the oven stage is the same short blast whatever the size.
| Joint weight | Simmer (20 min per 450g + 20 min) | Then glaze-roast at 200°C fan | Roughly serves |
|---|---|---|---|
| 1 kg | about 1 hour 5 minutes | 20 minutes | 4–5 |
| 1.5 kg | about 1 hour 30 minutes | 20 minutes | 6–7 |
| 2 kg | about 1 hour 50 minutes | 20–25 minutes | 8–10 |
| 2.5 kg | about 2 hours 10 minutes | 25 minutes | 10–12 |
| 3 kg | about 2 hours 35 minutes | 25 minutes | 12–14 |
Allow roughly 200g of cooked ham per person, a little more if you are counting on cold cuts for Boxing Day, which you should be.
Treat the times as a guide rather than gospel: the real test of doneness is the centre reaching 70°C on a probe. Add 15 to 20 minutes for a joint cooked on the bone, which holds and conducts heat differently from a boneless one.
The thrifty centrepiece. A ham is the most economical showpiece on the Christmas table. A 2kg supermarket gammon costs a fraction of the turkey, feeds eight to ten, and the leftovers stretch for days. Save the cooking liquid when you lift the joint out, too — strained, it is the base of a fine pea and ham soup, so very little is wasted.
Do you need to soak it?
Usually not. Modern supermarket gammon is cured mild enough to cook straight away. Soak overnight in cold water only if the label says so, or if it is a heavily cured joint from a traditional butcher and you are sensitive to salt. The quicker insurance, if you are unsure, is to bring it to the boil in its first lot of water, tip that water away, then start again with fresh — it draws out the worst of the salt without the overnight wait.
Scoring and studding: the part that looks hard and is not
Once the skin is off, leaving a smooth layer of fat, the diamonds take two minutes and turn a plain joint into a centrepiece.
Four glazes, and when to brush them
Whatever you choose, brush it on only for the roasting stage and re-brush once halfway. Glaze from the start and the sugar scorches long before the surface is lacquered.
| Glaze | What is in it | Character |
|---|---|---|
| Honey & mustard | 3 tbsp honey, 2 tbsp English mustard, 2 tbsp demerara | The classic — sweet, sharp, reliable |
| Marmalade | 4 tbsp fine-cut marmalade, loosened with a little hot water | Bright, citrus, faintly bitter |
| Treacle & mustard | 2 tbsp black treacle, 1 tbsp wholegrain mustard | Dark, rich, properly old-fashioned |
| Maple & clove | 4 tbsp maple syrup with a pinch of ground clove | Mellow and warm, good with smoked gammon |
Cook it ahead, serve it cold
This is the host’s secret and the reason a ham earns its place at Christmas. Cook and glaze the whole joint up to two days before, cool it completely, then keep it wrapped in the fridge. Served cold on Christmas Day or Boxing Day, carved thin with chutney, baked potatoes and the cheeseboard, it asks nothing of you and frees the oven entirely for the turkey. If you would rather serve it warm, either do the glaze-roast fresh on the day, which takes only 25 minutes, or reheat the cooked joint covered loosely with foil at 160°C fan until piping hot all the way through.
The slow-cooker method
A slow cooker is a fine way to free up the hob. Sit the gammon in the pot with the aromatics and a splash of water (no need to cover it fully), and cook on low for 6 to 8 hours, until tender. Then skin, score, glaze and finish in a hot oven at 200°C fan for 20 to 25 minutes exactly as above — the oven stage is what gives you the sticky finish, so do not skip it.
Storing, freezing and leftovers
Cool cooked ham completely, wrap it well and keep it in the fridge for three to four days. It freezes for up to a month; slice or portion it first so you can take only what you need, and thaw overnight in the fridge. As for leftovers, a Christmas ham is the gift that keeps giving: thick in sandwiches with mustard, through a pea and ham soup, folded into a carbonara, baked in a pie, or simply with eggs and chips on the quiet days between Christmas and New Year.
Christmas ham: your questions answered
What is the difference between gammon and ham?
Gammon is the raw cured joint; once it is cooked it becomes ham. You buy gammon and, after cooking, serve ham.
How long do you cook a gammon joint?
Simmer for 20 minutes per 450g plus an extra 20 minutes, then glaze and roast at 200°C fan for 20 to 25 minutes. A 2kg joint takes about 1 hour 50 minutes to simmer.
Do you boil or roast gammon?
Both, in that order. Simmering keeps the meat moist and tender; the short, hot roast at the end is what lacquers the glaze. Roasting alone tends to dry it out.
Do you need to soak gammon before cooking?
Usually not — modern gammon is mildly cured. Soak overnight only if the label advises it or the joint is heavily cured. Alternatively, boil it once, tip the water away and start again with fresh.
What temperature do you glaze a ham at?
200°C fan (220°C conventional, gas mark 7) for 20 to 25 minutes, brushing the glaze on only at this stage and again halfway. Lower the heat or tent with foil if it browns too fast.
Can you cook a Christmas ham the day before?
Yes, and it is the calmest plan. Cook and glaze up to two days ahead, cool and refrigerate, and serve it cold, or reheat gently. This keeps the oven free for the turkey.
Can you cook gammon in a slow cooker?
Yes. Cook on low for 6 to 8 hours with aromatics, then skin, glaze and finish in a hot oven for 20 to 25 minutes to get the sticky glaze.
How much gammon per person?
Allow about 200g of cooked ham each, and buy a little over if you want cold cuts for the following days.
Round out the Christmas table
A glazed ham loves good company. Serve it with a proper homemade cranberry sauce, Jamie Oliver’s braised red cabbage and crisp roast potatoes and parsnips, and a spoonful of proper homemade bread sauce. Counting down the days? See our weeks until Christmas. Cooking gammon outside the festive season? Our sister site has an everyday guide to how to cook a gammon joint, with a cooking-time calculator.
Written by Linda Garrould. Updated 14 June 2026.
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