Dissolve yeast and sugar in lukewarm water in a mixing bowl.

Heat milk and add shortening to dissolve, then let cool to lukewarm.

Add salt, egg yolks (slightly beaten), and sugar to the milk mixture.

Add the milk mixture to the yeast mixture.

Gradually add flour, mixing until all is incorporated.

Work the dough either by mixer or hand until it is glossy.

Cover and let rise until double in bulk, about an hour.

Divide dough and shape into kolaches, then fill with your choice of filling.

Bake until golden brown.