Dark Cocoa Hazelnut Cold-Rise Babka Buns

Warm the whole milk until just above body temperature (about 38°C/100°F). Stir in the yeast and 1 tablespoon of white sugar. Let stand 5 minutes until foamy.

In a large bowl or stand mixer, whisk together the all-purpose-flour, remaining cocoa powder, remaining white sugar, and salt.

Add the foamy yeast mixture and the egg to the flour. Mix on medium speed until a shaggy dough forms.

Add the softened butter a tablespoon at a time, letting each piece incorporate before adding the next. Continue kneading for 8–10 minutes until the dough is smooth, supple, and slightly tacky but not sticky.

Form the dough into a ball, place in a lightly oiled bowl, and cover tightly with plastic wrap.

Refrigerate for at least 8 hours or up to 16 hours. The slow cold rise deepens the cocoa flavor and develops a tender, airy crumb.

Toast the hazelnuts in a dry skillet over medium heat, tossing frequently, until golden and fragrant, about 5 minutes. Let cool slightly, then roughly chop.

In a small saucepan, melt the butter for the filling. Whisk in the cocoa powder and brown sugar until a thick, spreadable paste forms. Let cool to room temperature.

On a lightly floured surface, roll the cold dough into a large rectangle roughly 40cm x 30cm (16in x 12in). The dough will be firm — let it warm for a few minutes if it springs back.

Spread the cocoa filling evenly across the entire surface using an offset spatula or the back of a spoon.

Scatter the chopped hazelnuts evenly over the filling.

Starting from the long side, roll the dough tightly into a log. Use a bench scraper to help tighten the roll as you go.

Cut the log into 8 equal pieces (about 5cm/2in each). Place cut-side up in a greased 9-inch baking dish or arrange on a lined baking sheet, spacing 3–4cm apart.

Loosely cover the shaped buns with plastic wrap or a clean kitchen towel.

Let rise at room temperature for 45–60 minutes until puffy and nearly doubled. The dough should feel light and jiggles slightly when the pan is nudged.

Preheat the oven to 175°C (350°F).

Whisk the egg for the wash. Brush generously over the tops of the buns. Sprinkle a little white sugar over each for a sparkly crust.

Bake for 22–26 minutes until the tops are set,深色 and slightly firm to the touch. A toothpick inserted into the center should come out with just a few moist crumbs.

Let cool in the pan for 10 minutes before serving warm. These buns are best the day they're made, but will keep in an airtight container for two days.