1 c. chopped onion
1 lb. ground beef
1 tbsp. flour
1 c. milk
1 tsp. salt
3 egg whites
3 egg yolks
1 c. sour cream
2/3 c. flour
1/2 tsp. salt
1 1/2 c. grated cheese

Brown onion, ground beef and flour. Add milk and salt and cook until thickened. Beat egg whites until stiff. Beat together egg yolks, sour cream, 2/3 cup flour and salt. Pour half egg mixture into casserole. Top with 3/4 cup grated cheese. Bake 10 minutes at 400 degrees. Put on meat mixture, the remaining egg mixture and another 3/4 cup cheese. Bake 15 minutes more. Serve.