Makes 8 servings

Ingredients:

1/2 cup butter
1 sweet potato, cubed
2 small leeks, chopped
1 cup chopped celery
1 tablespoon chopped fresh thyme
3 cloves garlic, minced
1/2 cup all-purpose flour
4 cups milk
1 1/2 pound whitefish fillet, cut into 2" cubes
1 1/2 cup halved green beans, blanched
1 1/2 teaspoon salt
1/2 teaspoon freshly ground pepper
1 package frozen puff pastry sheets, thawed
1 large egg yolk
1 tablespoon water

Preheat oven to 400 degrees F.

Melt butter over medium-heat in a large stock pot oven. Sauté the potato, leeks, and celery for 10 minutes. Add thyme and garlic; cool 1 minute. Sprinkle flour over vegetables, and cook, stirring constantly, 3 minutes. Whisk in milk; bring to a boil. Reduce heat to low, and simmer 2 to 3 minutes or until potato is almost tender.

Add fish and next 3 ingredients; return mixture to a simmer. Remove from heat. (Fish will be under cooked.) Ladle filling into a medium sized baking dish.

Roll out one sheet of pastry on a lightly floured surface until smooth. Whisk together egg yolk and 1 tablespoon water; brush the underside of the pastry edges with egg wash and place over the baking dish, pressing edges to seal. Brush top with egg wash. Place on a baking sheet. Bake for 14-16 minutes or until pastry is golden brown.