Steps
- Dissolve 20g of fresh yeast in 80ml of water at about 100°F / 38°C. Mix 420g of all-purpose flour, 8g of sea salt, 60g of superfine sugar, and 20g of softened unsalted butter in a stand mixer.
- Add 20g of beaten egg, 110ml of whole milk, and the yeast mixture. Knead with a dough hook for 5 minutes on low, then 6-10 minutes on medium-high, until smooth.
- Wrap and rest for 10 minutes. Roll to 16 × 12in / 40 × 30cm, about ⅛in / 4mm thick; wrap and freeze for 1 hour.
- Roll 200g of cold unsalted butter between parchment to 8 × 12in / 20 × 30cm; chill until cold but flexible. Use butter with at least 82% fat.
- Center the butter on the dough and fold the short ends over to meet. Turn a quarter turn and roll to 16in / 40cm long, keeping its width; chill for 10-20 minutes if soft.
- Fold both ends to the center, then fold in half like a book. Chill for 30 minutes, turn a quarter turn, roll long again, fold both ends to the center, and chill for 30 minutes.
- Roll to 12½ × 12in / 32 × 30cm and cut 3 × 6in / 8 × 15cm rectangles. Use 16 dark chocolate batons across the batch, rolling each rectangle around two batons in succession; set seam-side down on lined sheets.
- Rise at 79-84°F / 26-29°C for 2-3 hours, until doubled. Preheat the oven to 350°F / 175°C, brush with beaten egg, and bake for 15-18 minutes, until golden and cooked through.