Prepare the yeast mixture: In a small bowl, combine warm milk, sugar, and yeast. Let it sit for about 5 minutes until foamy.

Make the dough: In a large bowl, mix flour and salt. Add the yeast mixture and combine until a dough forms. Knead the dough for about 5 minutes until smooth and elastic.

Shape the butter: Place cold butter between two sheets of parchment paper, flattening it into a rectangle about 1/2 inch thick. Chill in the refrigerator until firm.

Encapsulate the butter: Roll out the dough into a larger rectangle than the butter block, position the butter in the center and fold the dough over, sealing the edges well.

Repeat the process: Roll out the dough and fold it two more times, chilling in between each fold.

Cut and shape: Roll out the laminated dough into a rectangle about 1/4 inch thick. Cut into triangles and roll each from the base to the tip.

Let them rise: Cover the croissants and let them rise in a warm place until doubled in size, about 1-2 hours.

Bake to perfection: Preheat your oven to 375°F (190°C), brush the croissants with beaten egg, and bake for 15-20 minutes until golden brown.

Cool and serve: Allow croissants to cool slightly before serving. Enjoy warm or at room temperature.