Preheat oven to 350 degrees F. Grease casserole dish.
Melt butter in a pan. Add the 3 tablespoons flour. Mix until it becomes a smooth paste. Add milk and heat on low, stirring occasionally until it becomes slightly thicker.
Add chopped onion and stir in with other ingredients. Stir in grated cheese, and heat on low until melted. Separate egg whites from yolk. Beat egg yolk and add to other ingredients in pan. Vigorously beat the egg whites, until they are foamy then fold into pan with the rest of the ingredients.
Pour blended ingredients into the greased casserole dish and bake at 350 degrees F for 1 hour. Periodically check to make sure that it is cooking evenly, not burning.
Enjoy!
By Cathy from South Pasadena, CA
Related: 
Spinach Souffle
By
08/23/2011
My mom has always loved Morrison's Spinach Souffle. This will be a good recipe to fix for her. Thanks
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