Yeast Cakes - Kolače

Dissolve yeast in 1/4 cup of lukewarm milk with 2 tsp of sugar and let stand until it rises.
In a large mixing bowl beat butter, sugar, and eggs until smooth. Then add grated lemon peel and lukewarm milk. After yeast has risen, add to first mixture and add flour. Mix well, kneading into smooth dough. Cover and place near heat to rise until it doubles.
After dough rises, cut it into small pieces, roll into small balls and place on a well greased pan about 2 inches apart. Place near heat and let rise again.
While the dough is rising make the crumbly topping. Cut butter into flour until small crumbs form then add in sugar.
Upon rising, make dents in the center and brush lightly with well beaten egg. Fill with your choice of poppy seeds, cottage cheese or any kind of jam. Sprinkle top with crumbs and bake in 400 F oven for 15 - 20 minutes.