Equipment
Ingredients
Leeks and Ham
- 8 leeks, trimmed, white and light green parts only
- 8 cooked ham, sliced thinly
Mornay Sauce
- 50 g unsalted butter
- 50 g all-purpose flour
- 500 ml whole milk, warm
- 10 g dijon mustard
- 1 g ground nutmeg, freshly grated
- 150 g gruyere cheese, freshly grated
- salt
- black pepper
Topping
- 30 g panko breadcrumbs
- 30 g parmesan cheese, freshly grated
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 715 kcal
- Protein
- 40 g
- Carbohydrates
- 65 g
- Fat
- 37 g
- Fiber
- 6 g
- Sugar
- 19 g
- Sodium
- 1287 mg
- Saturated Fat
- 17 g
- Monounsaturated Fat
- 8 g
- Polyunsaturated Fat
- 2 g
- Cholesterol
- 86 mg
- Potassium
- 967 mg
- Calcium
- 808 mg
- Iron
- 7.8 mg
- Magnesium
- 120 mg
- Phosphorus
- 680 mg
- Zinc
- 2.7 mg
- Vitamin A
- 509 mcg
- Vitamin C
- 36 mg
- Vitamin D
- 1.9 mcg
- Vitamin E
- 3.3 mg
- Vitamin K
- 144 mcg
- Vitamin B6
- 0.8 mg
- Vitamin B12
- 1.3 mcg
- Thiamin
- 0.36 mg
- Riboflavin
- 0.47 mg
- Niacin
- 2.0 mg
- Folate
- 214 mcg
- Water
- 378 g
Sources: Aggregated Public Data, USDA FoodData Central
Method
Bring a large pot of salted water to a boil. Slice off the dark green tops and the root ends of the leeks. Peel away the tough outer layer.
Add the prepared leeks to the boiling water and cook until tender when pierced with a knife, about 15 minutes.
Carefully remove the leeks from the water using tongs or a slotted spoon. Place them on a clean kitchen towel and gently press them to extract as much excess water as possible.
Preheat the oven to 200°C/400°F. Grease a 9x13 inch baking dish.
Wrap each drained leek tightly in a slice of ham. Arrange them in a single layer in the prepared baking dish.
Melt the butter in a medium saucepan over medium heat. Whisk in the flour and cook for 2 minutes to cook out the raw flour taste, forming a pale roux.
Gradually whisk in the warm milk, pouring in a steady stream while whisking constantly to prevent lumps. Simmer for 5 to 7 minutes until the sauce heavily coats the back of a spoon.
Remove the saucepan from the heat. Whisk in the Dijon mustard, nutmeg, and the grated Gruyere cheese until completely smooth. Taste and season with salt and black pepper.
Pour the cheese sauce evenly over the ham-wrapped leeks in the baking dish. Mix the panko breadcrumbs and grated Parmesan cheese together, then scatter this mixture over the top.
Bake in the preheated oven at 200°C/400°F for 20 minutes, until the sauce is bubbling heavily around the edges and the crumb topping is deep golden brown.
Let the casserole rest for 5 to 10 minutes before serving to allow the sauce to set slightly.
Chef's Notes
- Draining the leeks is the single most important step in this recipe. Leeks act like sponges; failing to press them dry will result in a split, watery sauce.
- For the highest quality Mornay sauce, always grate your own Gruyere from a block. Pre-shredded cheeses are coated in starches that interfere with a smooth melt.
- If your leeks are particularly thick, you may want to slice them in half lengthwise before wrapping them in ham, which reduces the boiling time and makes them easier to eat.
- Warming the milk before adding it to your roux helps prevent seizing and lumps, leading to a silkier bechamel base.
Storage
Refrigerator: 3 days — Store in an airtight container. The breadcrumb topping will lose its crispness.
Reheating: Reheat in a 180C oven for 15-20 minutes until bubbling and heated through.
Troubleshooting
The casserole has a puddle of watery liquid at the bottom
Cause: The boiled leeks were not thoroughly drained before assembly
Fix: Carefully tilt the dish and use a turkey baster or spoon to extract excess liquid, then return to oven for 5 minutes
Prevention: Press the leeks firmly between clean kitchen towels before wrapping in ham
Cheese sauce is grainy or separated
Cause: Cheese was added while the pan was still on active heat, or pre-shredded cheese with anti-caking agents was used
Fix: Cannot be fixed once fully split, but an immersion blender can sometimes partially re-emulsify it if caught before baking
Prevention: Always remove the bechamel from heat before stirring in freshly grated cheese
Roux has hard lumps when milk is added
Cause: Cold milk was added too quickly to the hot roux
Fix: Vigorously whisk the sauce or pass it through a fine-mesh sieve before adding the cheese
Prevention: Warm the milk before incorporating, and whisk continuously while adding it in a thin stream
Cultural Context
Known in France as Poireaux au Jambon, this comforting bistro classic is a beloved winter staple in both French and Belgian home cooking. It transforms humble, sweet alliums into a decadent centerpiece by pairing them with salty cured pork and a rich Mornay sauce.
