Piskota fank-(hungarian doughnuts with cream)

1. Beat butter until creamy, beat in 4 whole eggs, beat in 4 egg yolks, add sugar and sour cream, add flour and the yeast mixutre.
2. Beat until smooth, set aside to rest and rise until doubled in size.
3. Place on board that has been dusted with flour.
4. Roll out to ¾ inch thickness, cut with doughnut cutter.
5. Put in greased pan, lat raise 40 minutes.
6. Brust top with beaten egg. Bakei in 350°F oven for ½ hour.
7. For cream mix; cook milk, egg yolks and sura over low heat, in double boiler until mixture is smooth.
8. Stirring all the while, cool and pour over doughnuts and serve.