1. Preheat oven to 190°C.
2. Melt 1 tablespoon butter in medium skillet over medium heat and lightly sweat leeks, about 3 minutes.
3. Melt remaining 3 tablespoons butter in medium saucepan over medium heat, then stir in flour. Cook, stirring constantly, 1 minute. Slowly stir in milk until mixture is thickened. Stir in cheese, Maille Dijon Mustard and season with salt and freshly ground black pepper. Stir in leeks and hot macaroni.
4. Pour mixture into a medium sized baking dish and bake 20 minutes or until bubbling and golden.
1. Garnish with parsley.
2. Serve with a few strips of bacon, thinly sliced and fried crisp.
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