In a mixer with a dough attachment, combine 375g plain flour, 1 teaspoon salt, 50g caster sugar, 7g yeast, 75g milk, and 3 large eggs. Mix for 5 minutes until the dough is smooth. 2. Add 180g butter to the mixer. Mix for an additional 4 minutes on medium speed. 3. Scrape down the sides of the mixing bowl. Mix again for 1 minute. 4. Transfer the dough to a container. Cover the container with cling film. Place in the fridge for a minimum of 6 hours. 5. Wrap the 250g Brie cheese with the 8 slices of prosciutto. Set aside. 6. Lightly flour a clean work surface. Turn the dough out onto the floured surface. 7. Roll the dough into a circle approximately 25cm in diameter. 8. Place the prosciutto-wrapped Brie in the center of the dough circle. Fold the edges of the dough neatly over the Brie to fully enclose it. 9. Line a baking tray with baking parchment. Carefully place the dough parcel onto the prepared baking tray. Brush the entire surface of the dough with a beaten egg. 10. Refrigerate the baking tray with the dough for 30 minutes. 11. After 30 minutes, remove from the fridge. Brush the dough again with a beaten egg. 12. Return to the fridge for another 30 minutes. 13. Remove the baking tray from the fridge. Let the dough rise at room temperature for 1 hour. 14. Preheat your oven to 200°C (180°C for fan-assisted ovens or Gas Mark 6). 15. Bake for 22 minutes. 16. Serve warm.