Bring a pot of water to a boil and add a large pinch of salt. Blanch the green beans until they are crisp yet tender, about 2 minutes. Shock them in a bowl of ice water until cold. Drain well and set aside in a bowl.

Preheat the oven to 375º.

Heat a saucepan over medium heat and add the butter. Gently sauté the leeks until tender, and season with salt and pepper to taste.

Sprinkle in the flour and cook for 1 minute to cook out the raw starchy taste. Slowly whisk in the vegetable stock and cream, and cook until thickened, stirring occasionally, about 10 minutes. Stir in the mustard, peppers and chives, and season with salt and pepper to taste.

Pour the sauce into the bowl with the green beans, and toss to coat.

In a small bowl toss together the breadcrumbs, almonds and olive oil. Sprinkle on top of the green beans, and bake until the top is golden brown and the green beans are hot, about 30 minutes.

Note:

To roast a pepper, place it directly on your gas burner and cook, turning occasionally, until the skin is completely blackened on all sides. Place the pepper in a bowl, cover with plastic wrap and allow to steam for about 15 minutes. Remove the skin and seeds from the pepper, resisting the urge to rinse it, and cut as needed for your recipe.