2 1/4 teaspoons active dry yeast
1/4 cup warm water
1/2 cup milk, warmed
1/4 cup granulated sugar
1/2 teaspoon salt
1 egg
2 1/2 cups all-purpose flour
1 cup unsalted butter, cold
1/2 cup fruit jam or pastry filling
1 egg yolk
1 tablespoon milk
Dissolve yeast in warm water
Stir in warm milk, sugar, salt, egg, and flour
Mix until a soft dough forms
Knead until smooth
Chill dough
Pound cold butter into a flat rectangle
Roll dough into a rectangle
Place butter on half of the dough
Fold dough over butter
Roll and fold several times
Chill between folds
Roll dough to final thickness
Cut into squares or rectangles
Add filling to the center
Fold or shape the dough
Place on a baking sheet
Cover and let rise until puffy
Mix egg yolk with milk
Brush tops with egg wash
Bake at 400°F until golden brown
Cool slightly before serving