Mix warm milk and yeast in a bowl; let it sit until frothy (about 5-10 minutes).
In a large bowl, combine flour, salt, and sugar.
Add the frothy yeast mixture and melted butter; mix until a dough forms.
Knead on a floured surface for about 5 minutes until smooth.
Wrap the dough in plastic wrap; refrigerate for 1 hour.
Place cold butter between two sheets of parchment paper; pound and roll it into a rectangle (about ½ inch thick).
Roll out the chilled dough; place the butter block in the center and fold dough over it.
Roll out and fold into thirds; refrigerate for 30 minutes. Repeat the rolling and folding process two more times.
Roll out the final dough, cut into triangles, and roll from the base to the tip to form crescents.
Place the shaped gipfeli on a baking sheet; cover and let rise for about 30 minutes.
Preheat oven to 400°F (200°C).
Brush with beaten egg; bake for 15-20 minutes until golden brown.