Add yeast and 1 teaspoon of sugar to 1/4 cup of the scalded milk cooled to lukewarm. Set aside to cool. To the rest of the hot milk add the butter, sugar, salt and vanilla and stir until the butter has melted. Cool. Add the beaten eggs and then stir in the yeast. Sift flour and add gradually, using only enough to knead the dough until it is smooth and elastic. Cover and allow to rise until double in bulk. Roll out on a floured board until quite thin; cut into triangles, spread with poppys seed filling (see recipe below) and shape into cresents by rolling them from the straight end toward the point. Brush with beaten egg yolk to which 1 tablespoon of cold water has been added and sprinkle with sugar and chopped nuts. Let rise until doubled in bulk and then bake in a hot oven 400-F about 20 minutes or until brown. Filling: Boil the water with the sugar until syrupy, add the ground poppy seeds, cinnamon and lemon rind. Mix well and allow to cool.