In a large mixing bowl, combine flour, sugar, and salt. In a separate bowl, dissolve yeast in warm milk, then mix into the flour mixture and knead for 5-7 minutes until smooth. Cover and refrigerate for 1 hour.

Prepare the butter block by placing cold butter between two sheets of parchment paper and shaping it into a 6-inch square. Keep it cold.

Roll the chilled dough into a 12-inch square, enclose the butter block, and roll it out into a long rectangle. Fold into thirds, wrap, and chill for 30 minutes.

Perform the first turn by rolling out the dough and folding it into thirds. Chill for another 30 minutes. Repeat two more times for a total of three turns.

After the final chilling, roll the dough to 1/4-inch thickness, cut into triangles, and roll into crescent shapes. Allow to rise for 1.5 to 2 hours.

Preheat your oven to 400°F (200°C). Prepare an egg wash, brush croissants, and bake for 18-22 minutes until golden brown. Cool on a wire rack.