1. Scald milk and allow it to cool to lukewarm. Add yeast and stir until softened.
2. Beat the egg yolks until thick. Add the yeast mixture and remaining ingredients except egg whites. Mix thoroughly.
3. Set in a pan of warm water, cover and let rise until double in bulk, about one and one-quarter hours.
4. Beat egg whites stiff and fold gently but thoroughly into batter.
5. Preheat a lightly buttered griddle until it is hot. Using one tablespoon of batter for each pancake, bake on top of stove until golden brown, turning once. If the blini begin to stick to the griddle, butter it lightly again.