Brioche au Chocolat Swirls

Prepare the Dough

1. If using homemade brioche dough, ensure it has completed its first rise and has been briefly chilled for easier handling. If using store-bought, let it come to a cool room temperature.
2. On a lightly floured surface, roll out the brioche dough into a large rectangle, approximately 12x18 inches (30x45 cm) and about 1/4 inch (0.6 cm) thick.

Prepare the Chocolate Filling

1. In a small bowl, combine the finely chopped dark chocolate, melted unsalted butter, and granulated sugar. Mix until well combined and spreadable. The mixture might be chunky, which is fine.

Assemble the Swirls

1. Evenly spread the chocolate filling over the entire surface of the rolled-out brioche dough, leaving a small border (about 1/2 inch) on one of the long edges.
2. Starting from the opposite long edge (the one with no border), carefully roll the dough into a tight log.
3. Using a sharp knife or unflavored dental floss, cut the log into 8 equal slices, approximately 1.5 inches (4 cm) thick.
4. Lightly grease and flour (or line with parchment paper) a 9-inch (23 cm) round baking dish or individual muffin molds. Arrange the brioche swirls evenly in the prepared dish or molds, leaving some space between them as they will rise.

Proof and Bake

1. Cover the dish loosely with plastic wrap or a clean kitchen towel and let the brioche swirls proof in a warm place for about 1 to 1.5 hours, or until they have nearly doubled in size.
2. Preheat your oven to 375°F (190°C) during the last 15 minutes of proofing.
3. In a small bowl, whisk together the egg and milk for the egg wash. Gently brush the top of each brioche swirl with the egg wash.
4. Bake for 20-25 minutes, or until the brioche is golden brown and cooked through. If they start to brown too quickly, you can loosely tent them with aluminum foil.
5. Remove from the oven and let cool slightly on a wire rack before serving warm or at room temperature.