1 jar spaghetti sauce and 1 lb. ground beef (together for meat sauce)
1 box lasagna, cook and have ready
4 tbsp. flour
2 c. milk
1 sm. onion, chopped
2 egg yolks
8 tbsp. butter
3/4 c. Parmesan cheese

Cook onions in butter. Mix in flour. Add cheese and a dash of salt. Gradually stir in milk and cook over low heat, stirring constantly until thick. Beat egg yolks; add a little cheese sauce to yolks and then add yolks-cheese sauce to remainder of cheese sauce. Cook, low heat, for 10 minutes.

Layer the meat sauce, noodles, and cheese sauce. Sprinkle Parmesan cheese (or Mozzarella) on top. Bake at 350 degrees for 20 minutes or until heated through. Then broil until cheese is golden.