This is a good mid week recipe, you can vary the veg used for something you prefer - in France endives are often used and I've made this with small florets of broccoli before. If you don't have Mozzarella just grate whatever cheese you have in the fridge.
1. Prepare the veg by peeling and chopping the potatoes and onion. Trim and clean the leeks. Bring the potatoes to the boil then simmer for 10 minutes until almost cooked. Drain the potatoes, mix with the onion, black pepper and a tablespoon of olive oil and put into a baking dish. Place the leeks into boiling water for 3 minutes and then drain well. Prepare the bechamel sauce - recipe here. I made a double quanity.
Pour the remaining sauce over the ham and leek rolls then arrange the sliced mozzarella on the top. Cook at 180°C for about 20 minutes and then brown the cheese under the grill.
This dish doesn't need anything else but it's still nice to serve it with a hot crusty baguette.
Photo added just because I like it!