Prepare the Dough: In a bowl, dissolve yeast in warm milk and let sit for 5-10 minutes until foamy. In a separate bowl, combine flour, powdered sugar, salt, and milk powder. Add the yeast mixture and knead until a soft dough forms. Incorporate butter and continue kneading for 8-10 minutes until smooth.
First Rise: Cover the dough and let it rise in a warm place for 1-1.5 hours, or until doubled in size.
Shape the Bread: Punch down the dough, shape it into rolls or a loaf, and place it in a greased baking pan. Cover and let rise for another 30-45 minutes.
Bake: Preheat the oven to 180°C (350°F). Brush the dough with egg yolk and sprinkle with sesame seeds if desired. Bake for 18-22 minutes or until golden brown and fluffy.
Cool & Serve: Let the bread cool slightly before serving. Enjoy warm or at room temperature!