In a small bowl, whisk together the warm milk, granulated sugar, and active dry yeast. Let it sit for about 5–10 minutes until frothy.

In a large mixing bowl, combine 2 1/4 cups of all-purpose flour and 1/2 teaspoon of salt. Whisk gently.

Add the melted butter, egg, and the frothy yeast mixture to the dry ingredients. Stir until a cohesive dough forms.

On a lightly floured surface, knead the dough for about 5 minutes until smooth and elastic. Place in a greased bowl and let it rise, covered, for about 1 hour.

Lay cold butter pieces on parchment paper and flatten into a rectangle about 1/2 inch thick. Chill while the dough rises.

Once the dough is ready, roll it into a large rectangle, approximately 12 × 18 inches.

Place the chilled butter block in the center of the dough. Fold the edges of the dough over the butter to seal it.

Roll out the dough again into a rectangle, then fold into thirds like a letter. Cover and refrigerate for 30 minutes. Repeat twice.

In a medium bowl, combine 1 cup of semi-sweet chocolate chips, 1/4 cup cocoa powder, 1/4 cup powdered sugar, and 1 teaspoon vanilla extract. Mix to create a smooth filling.

After the last chill, roll the dough into a large rectangle, around 12 × 24 inches.

Spread the chocolate filling over the dough, reaching the edges.

Starting from one long edge, tightly roll the dough into a log shape, pinching the seam to seal.

Position the rolled loaf seam-side down in a greased loaf pan and tuck in the ends.

Cover the loaf with a towel and let it rise for about 30 minutes.

Preheat your oven to 375°F (190°C).

Bake the loaf for 20–25 minutes until golden brown. Shield with foil if browning too quickly.

Let the loaf cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.

Optional: Dust with powdered sugar before serving.