1. Sprinkle dry yeast or crumble cake into water.
2. Let stand for a few minutes; then stir until dissolved.
3. Sift dry ingredients into large bowl.
4. Cut in 1/2 cup soft butter.
5. Add yeast and mix well.
6. Roll about 1/4 inch thick on floured board.
7. Cut with floured 2-inch cutter and put half on cookie sheets.
8. Brush with melted butter.
9. Top with remaining biscuits.
10. Beat egg yolk and 1 tablespoon water together.
11. Brush on biscuits.
12. Cover and let rise until doubled, about 1 hour.
13. Bake in preheated hot oven (425 °F.) for about 10 minutes.
14. Makes about 3 dozen biscuits.