New Brunswick Lobster Casserole

3 tablespoons butter, divided

3 tablespoons all-purpose flour

¾ teaspoon dry mustard

1 teaspoon salt

½ teaspoon pepper

1 cup milk

1 cup light cream

3 cups mushrooms, sliced

¼ cup shredded Swiss cheese

3 cups cooked lobster meat, diced

2 cups soft bread cubes

½ cup fine dry bread crumbs

2 tablespoons melted butter

Preheat oven to 350 degrees F (175 degrees C). Lightly grease a casserole dish.

Melt 3 tablespoons of butter in a saucepan over medium heat. Stir in flour, mustard powder, salt, and pepper until smooth. Pour in the milk and cream, bring to a simmer, and cook until thickened and smooth, stirring constantly. Add the mushrooms and cheese, stir until the cheese has melted. Fold in the diced lobster meat and the bread cubes.

Pour into prepared casserole dish. Mix the bread crumbs with the remaining 1 tablespoon of melted butter to moisten. Sprinkle the crumbs over the casserole.

Bake in preheated oven until the crumbs have browned, and the casserole is hot; about 30 minutes.