4 Alaska pollock fillets (4 to 5-ounces each)
2 cups milk
4 tablespoons butter
1/3 cup flour
2 cups grated Cheddar or Monterey Jack cheese, divided
1 teaspoon wholegrain mustard
Salt and pepper to taste
1/2 cup fresh white bread crumbs
Fresh rosemary sprig
DIRECTIONS: Add water to a large pan and bring to a simmer. Rinse any ice glaze from frozen Alaska Pollock under cold water. Turn off heat and gently add seafood to the pan. Return heat to a simmer. Once simmering, cover pan and cook 4 to 5 minutes for frozen seafood or 2 minutes for fresh/thawed fish. Turn off heat and let seafood rest for 5 minutes or until seafood is opaque throughout; drain.
Meanwhile, heat broiler/oven to medium-high (450oF). Place four individual gratin dishes, or one large shallow baking dish, in the lower part of the oven to warm.
To make the sauce, put the milk, butter, and flour into a nonstick saucepan. Heat, stirring constantly with a small whisk until the sauce thickens. Remove from the heat and add half the cheese, stirring until melted. Add the mustard; season with salt and pepper.
Remove Alaska Pollock fillets from poaching liquid; break into large chunks and place in the warm dishes. Pour the sauce over the fish. Sprinkle with breadcrumbs and rosemary sprigs; add remaining cheese over the top.
Broil for 3 or 4 minutes, until browned and bubbling. Garnish with extra rosemary, if desired.