1. Peel and grate potatoes and onions. Soak crushed crackers in milk until soft.
2. Combine potatoes, onions, cracker mixture and grated cheese. Mix well.
3. Beat egg yolks slightly and add to potato mixture. Add salt and pepper. Mix well.
4. Beat egg whites until stiff but not dry and fold into potato mixture.
5. Spoon into well greased loaf pan. Bake in 350 degree oven for 1 hour and 15 minutes or until potatoes are tender.
6. Invert on to a warm platter. Slice to serve.