01 - Combine warm milk and active dry yeast in a mixing bowl and allow to sit for 5 minutes until foamy.
02 - Incorporate granulated sugar, salt, softened butter, and 1 large egg into the activated yeast mixture. Stir to blend evenly.
03 - Gradually add all-purpose flour, mixing until a sticky dough develops. Knead the dough for 5 to 7 minutes until smooth and elastic forms.
04 - Form dough into a ball, cover, and refrigerate for 30 minutes to rest.
05 - Roll cold unsalted butter between two sheets of parchment paper into a 5 x 8-inch rectangle. Chill until firm and ready to use.
06 - Roll out dough on a lightly floured surface into a 10 x 14-inch rectangle. Place the butter sheet on one half, fold the dough over the butter, and seal the edges tightly.
07 - Roll dough-butter package into a 20 x 8-inch rectangle. Fold into thirds like a letter. Cover and refrigerate for 30 minutes.
08 - Repeat the rolling and folding process two additional times, chilling 30 minutes after each fold to create flaky layers.
09 - Roll the finished dough into a 12 x 16-inch rectangle. Slice lengthwise into 8 even strips.
10 - Twist each strip gently into a spiral and coil into a snail shell shape, tucking the end underneath. Transfer each spiral onto a parchment-lined baking sheet.
11 - Cover spirals loosely with plastic wrap or a towel and let rise at room temperature for 1 to 1.5 hours until puffy and airy.
12 - Set oven rack in the center position and preheat to 400°F.
13 - In a small bowl, whisk together 1 egg and 1 tablespoon milk. Generously brush the egg wash onto each spiral for a glossy finish.
14 - Bake the spirals for 18 to 22 minutes until deep golden brown and crisp on the outside.
15 - Let cool slightly on the tray. Dust with powdered sugar if desired, and serve warm for best texture.