This is from an Amish cookbook.

3 tbsp. butter
3 tbsp. flour
1/4 tsp. salt
Dash pepper
1 1/2 c. hot milk
3 egg yolks, beaten
1 tbsp. grated onion
1 tbsp. minced parsley
1 lb. can salmon
1/2 c. mayonnaise
3 egg whites, stiffly beaten

Melt butter in top of double boiler, stir and blend in flour, salt, pepper. Add hot milk all at once, stirring constantly until smoothly thickened. Remove from heat. Stir in egg yolks, parsley, onion, salmon and mayonnaise. Fold in stiffly beaten egg whites and turn into buttered 2 quart casserole and bake at 350 degrees for 45 minutes.