Mix margarine, flour, salt and mustard in 3 quart saucepan over medium heat. Gradually stir in milk and cubed Velveeta, stirring constantly. When mixture is thickened, remove from heat and add undrained salmon and noodles. Place in 1 1/2 quart casserole and bake for 30 minutes at 350ºF. 

Salmon Noodle Casserole

4 ounces of fine egg noodles
One 7 3/4 ounce can of salmon, drained & flaked
1 cup of sour cream
1 cup of cream style cottage cheese
1/4 cup of finely chopped onion
1 tablespoon of poppy seeds
2 teaspoons of Worcestershire sauce
6 drops of Tabasco
1/4 teaspoon of seasoned salt
Dash pepper
1/4 cup of grated Parmesan cheese

Preheat oven to 350ºF. Cook noodles according to package directions. Combine with remaining ingredients, except Parmesan. Place in greased, 1 1/2 quart casserole. Sprinkle with cheese. Bake 25-30 minutes or until heated through.

Salmon Noodle Casserole

One 16 ounce can of salmon
Water
2 tablespoons of onion, chopped
4 tablespoons of butter
3 tablespoons of flour
2 tablespoons of horseradish
1 1/2 teaspoon of salt
1/4 teaspoon of pepper
One 14 1/2 ounce can of evaporated milk
2 cups of cooked noodles
1 cup of peas, cooked or whole kernel corn

Drain and flake salmon. Measure salmon liquid and add enough water to make 1 cup. Cook onion in butter until tender, but not browned. Remove from heat. Blend in flour and seasonings. Gradually add milk, mixing until smooth. Add water. Mix well. Cook over low heat, stirring until thickened and smooth. Arrange alternate layers of noodles, salmon, peas or corn in greased 1 1/2 quart casserole. Bake in hot oven, 400ºF. for 25-30 minutes or until top bubbles and is lightly browned. Serves 4-5.