Chef Thomas
Anglesey Eggs
Eggs bedded into leek-flecked mash under a blanket of sharp cheese sauce, baked until golden and bubbling. A Welsh supper dish that proves the simplest things are usually the best.
Culinary Explorer
A cooking platform built around craft, culture, and the stories behind what we eat.
Leek and Cheese Gratin
Created by Chef Thomas
Fat leeks laid in a dish, blanketed in a mustard-spiked cheese sauce, and baked under golden breadcrumbs until the whole thing blisters and bubbles and the kitchen smells like the evening you needed.
Main Dishes
British
Weeknight
Comfort Food
25 min
Active Time
35 min cook•1 hr total
Yield4 servings
January. Rain on the window and the light gone by half four. The leeks at themarket this morning were beautiful, fat and pale with mud still clinging to the roots, the sort that feel heavy and cold in your hand and smell faintly of the earth they came from. I bought six without a plan and the plan arrived on the walk home: gratin.
A leek and cheese gratin is not a complicated thing. It doesn't pretend to be. You soften the leeks, make a cheese sauce, put one on top of the other, and bake it until it blisters. The leek does the real work here, going sweet and silky under that bubbling crust, and the sauce is just there to carry the cheese where it needs to go. A recipe is a conversation, not a contract. If you want to add a scraping of garlic to the sauce, do. If you've got some thyme, tuck it in with the leeks. Your kitchen, your rules.
This is the kind of supper I come back to when the weather turns and the evenings close in. There are few better feelings than carrying a blistering dish to the table and watching someone's face when the smell hits them. We're only making dinner. But sometimes dinner is the whole point of the day.
I wrote it down in the notebook last Tuesday: leeks, cheese sauce, breadcrumbs, the good cheddar. Rain. Ate it with bread and didn't speak for ten minutes. That's a review.
The technique, the tradition, and the story behind every dish.
Discover Culinary ExplorerIngredients
leeks
Quantity
6 large
trimmed and cut into 4cm lengths
unsalted butter
Quantity
50g, plus extra for the dish
plain flour
Quantity
40g
whole milk
Quantity
500ml
strong mature cheddar
Quantity
150g
coarsely grated
English mustard
Quantity
1 teaspoon
whole nutmeg
Quantity
for grating
fine sea salt
Quantity
to taste
black pepper
Quantity
to taste
fresh breadcrumbs
Quantity
50g
Parmesan
Quantity
30g
finely grated
| Ingredient | Quantity |
|---|---|
| leekstrimmed and cut into 4cm lengths | 6 large |
| unsalted butter | 50g, plus extra for the dish |
| plain flour | 40g |
| whole milk | 500ml |
| strong mature cheddarcoarsely grated | 150g |
| English mustard | 1 teaspoon |
| whole nutmeg | for grating |
| fine sea salt | to taste |
| black pepper | to taste |
| fresh breadcrumbs | 50g |
| Parmesanfinely grated | 30g |
Equipment Needed
- •Large saucepan for blanching
- •Heavy-bottomed saucepan for the sauce
- •Baking dish, roughly 25cm x 18cm
- •Whisk or wooden spoon
- •Box grater
Instructions
- 1
Cook the leeks
Bring a large pan of well-salted water to the boil. Drop in the leek pieces and let them cook for five to seven minutes, until they're soft enough that a knife slides through without resistance but they still hold their shape. You're not after mush. Drain them thoroughly in a colander, then spread them on a clean tea towel and press gently to get out as much water as you can. Wet leeks make a watery gratin, and a watery gratin is a sad thing.
Split the leeks lengthways before washing them. Grit hides between the layers and no amount of rinsing the outside will get it out. Fan the layers under cold running water and let it flush through. - 2
Make the cheese sauce
Melt the butter in a heavy saucepan over a medium heat. When it foams, add the flour and stir constantly for a minute or so. It should smell biscuity and look like wet sand. Pour in the milk gradually, a good splash at a time, stirring or whisking between each addition until smooth before adding the next. Take your time here. Rushing the milk in makes lumps, and lumps are difficult to forgive. Once all the milk is in, let the sauce simmer very gently for five minutes, stirring often, until it coats the back of a spoon and tastes of nothing raw or floury.
If it does go lumpy, don't panic. A good whisk and some persistence will sort most of it. Failing that, push it through a sieve and carry on as though nothing happened. - 3
Season the sauce
Take the pan off the heat. Stir in most of the cheddar, keeping a small handful back for the top. Add the mustard, a generous grating of nutmeg, and season with salt and pepper. Taste it. The sauce should be savoury and warm, with a quiet mustard heat at the back. If it tastes bland, it needs more salt. Trust your tongue.
- 4
Assemble the gratin
Set the oven to 200C/180C fan. Butter a baking dish, something that fits the leeks in a snug single layer with a little room to spare. Lay the leeks in the dish, cut sides facing up where you can. Pour the cheese sauce over them, letting it settle into the gaps. Toss the breadcrumbs with the reserved cheddar and the Parmesan, then scatter the mixture evenly over the top.
- 5
Bake until golden
Bake for twenty-five to thirty minutes, until the top is deeply golden and the sauce is bubbling up around the edges in thick, lazy bursts. The kitchen will smell of toasted cheese and something warm and oniony and right. Let it sit for five minutes out of the oven before you serve it. The sauce needs a moment to settle, and so do you. Good bread on the side, or a green salad dressed sharply to cut through the richness. Nothing more.
Chef Tips
- •The cheese matters. Use a strong, mature cheddar that tastes of something when you eat a piece on its own. A mild cheddar will melt into nothing and the sauce will taste like flour and milk. You don't need much, but what you use should be worth eating.
- •Draining the leeks properly is the difference between a gratin with backbone and a puddle with breadcrumbs on top. Lay them on a tea towel after draining and press gently. You'll be surprised how much water they give up.
- •English mustard in the sauce is not optional. You won't taste it as mustard. What it does is sharpen the cheese and lift the whole thing so it doesn't sit heavy. A teaspoon is enough. You're waking the sauce up, not setting it on fire.
- •If you have leftover roast chicken, tear some into the dish with the leeks. It stops being vegetarian, but it becomes the sort of meal people ask you to make again.
Advance Preparation
- •The whole gratin can be assembled up to a day ahead and refrigerated, unbaked. Add five to ten minutes to the baking time if cooking from cold.
- •The cheese sauce can be made several hours in advance. Press a piece of cling film directly onto the surface to stop a skin forming, then reheat gently before assembling.
- •Leftovers reheat well in a moderate oven for fifteen minutes, covered loosely with foil to stop the top burning before the centre warms through.
Frequently Asked Questions
Nutrition Information
1 serving (about 300g)
Calories
540 calories
Total Fat
31 g
Saturated Fat
19 g
Trans Fat
0 g
Unsaturated Fat
12 g
Cholesterol
85 mg
Sodium
800 mg
Total Carbohydrates
46 g
Dietary Fiber
4 g
Sugars
14 g
Protein
21 g
Where cooking meets culture.
Culinary guides, cultural storytelling, and the editorial depth that makes cooking meaningful.
Discover Culinary ExplorerMore from Weeknight Suppers & Simple Fish
Browse the full collection
Chef Thomas
Bacon Carbonara
A cold evening carbonara made with good smoked back bacon, eggs, Parmesan, and more black pepper than seems reasonable, tossed together in the time it takes to boil the pasta.
Chef Thomas
Bacon Chops with Mustard Glaze
Thick bacon chops, bronzed in butter and slicked with a mustard and honey glaze that catches and caramelises under a hot grill. Twenty minutes, two plates, a very good Tuesday.
Chef Thomas
Cheesy Pasta Bake with Vegetables
Pasta shells folded through a leek-flecked cheese sauce with broccoli, baked until the top blisters gold and the whole kitchen smells like the kind of evening you want to sit down to.