Chocolate Swirl Buns

Dough

• 4 oz unsalted butter, softened, cut into pieces, plus extra to grease
• 7 oz whole milk
• 1 tbsp active dry yeast
• 2 large eggs
• 2 - 3 oz sugar, to taste
• 1 tsp salt
• 17 ½ oz bread flour

Chocolate Filling

• 6 ½ oz whole milk
• 6 oz half and half
• 2 large eggs
• 2 egg yolks, from large eggs, divided
• 2 oz sugar
• 1 oz unsweetened cocoa powder
• ½ oz bread flour, plus extra to dust
• 2 oz pearl sugar, to sprinkle
  o bien 2 oz turbinado sugar, to sprinkle